Scenario 1 - Zarbon decides to betray Freeza and interrogates Vegeta on the Dragon Balls, still able to gain nothing before Vegeta dies. He tells Bulma there only option will be to hide from Freeza and find the Dragon Balls before the Ginyus arrive. Kuririn takes Zarbon to Saichoro's house as a last resort and the Grand Elder views his redemption as honest before unlocking his potential. Kuririn then teaches Zarbon how to suppress his Ki and along with Gohan, they silently approach the Dragon Balls. Unfortunately, they cannot summon Porunga and were still putting forth enough power that the Ginyus notice them. With his potential unlocked and making a similar increase to Kuririn, Zarbon's new power allows him to deal with the Ginyus before they can take the Dragon Balls and before Gurd has a chance to freeze time or Ginyu can body change. When Goku arrives, they tell him the situation and he heads to Saichoro to get his potential unlocked. Around that time, Freeza arrives there and Goku fights him, his new power making up for the Zenkai he'd normally get from Ginyu. As such, Freeza quickly goes into his true form and the fight takes a similar direction to their warm up in canon. Whilst this happens, Nail concedes there's no longer anything he can do to protect Saichoro and helps bring Dende to his allies quickly so they can summon Porunga. Piccolo is revived and brought to Namek. Meanwhile, Freeza quickly goes into 50% and knocks Goku into the sea before rushing to their location.
Before the third wish can be made, an enraged Freeza arrives and quickly kills Zarbon for his betrayal. Seeing the Namekians nearby, he takes Dende hostage and threatens to kill him unless Nail makes him immortal. Just in time, however, Goku arrives after having ate a Senzu and increased his power. As the two continue their fight, Goku uses Kaioken x20 and is able to maintain it slightly better due to his Zenkai and even overpower Freeza with it, though it still runs out before he can do much more. Piccolo soon arrives and Nail demands he fuse with him for whatever good it may do. In his anger at Goku being able to hurt him so much, he injures Goku before killing Kuririn as an example. Goku goes Super Saiyan and tells Dende to wish for everyone but Goku and Freeza to be brought to Earth, whilst preventing Freeza from stopping him. The fight then occurs as you'd expect - 100% Freeza is no match for Goku, with him attempting to destroy the planet. With his increased power, I'll assume it takes less time, so let's say 2 minutes. This is still enough time for Goku to conclude the fight as he did in canon and find a ship. I'll say that his ship is still sunk due to being in close proximity to the blast and unable to pilot Freeza's ship, he takes a Ginyu pod as in canon.
Meanwhile on Earth, Kami informs Saichoro that Namek has been destroyed. Unfortunately, this means that the victims of Freeza can't be revived without dying again and their souls can't all be brought to Earth as a group, leading to Saichoro dying with Dende as his heir and one of the last Namekians, coming under Kami's tutelage as the next Kami. Yamcha is still brought back to life, whilst Kuririn, Ten and Chaozu remain dead.
1 year later, Freeza and King Cold come to Earth, though Goku uses Shunkan Ido to stop them before they can do anything. As in Trunks' timeline, the heart virus kills Goku and #17 and #18 bring about an apocalyptic scenario. Without Trunks, however, Gohan is far more cautious in his actions and waits until Bulma can build a time machine, taking Trunks' place in this story.
As in Trunks' version of events, Gohan kills Freeza and Cold before telling Goku everything. As Trunks' future isn't in the balance, he's open to his identity with everyone, with the Son family wanting him to stay with them. In the 3 year training, Future Gohan's inclusion allows them and Piccolo to all get far stronger. When #19 and #20 show up, Future Gohan quickly tells them that they aren't the ones from his future and to keep the old man alive for questioning. Goku quickly destroys #19 and the heart virus doesn't take effect, Future Gohan having made sure his father took the vaccine. This happening before Yamcha can arrive, Goku falls victim to Gero draining his energy before departing. He then takes a senzu before continuing to chase him, with Gero sneaking about to try and gain more power. He targets Piccolo, only to end up where he did in canon once the Super Saiyans show up. Once the lab is found and #16, #17 and #18 are activated, #16 wastes no time in killing Goku. The anger both Gohans feel from seeing this causes their rage to reach new heights as the present Gohan achieves Super Saiyan and their rage boosts allow them to overpower #16, destroying him. All that rage soon dissipates for present Gohan, though future Gohan still maintains some as he fights #17 and #18. Though the rage boost isn't able to last much longer, his regular Super Saiyan self is able to hold his own against #17 whilst his present self overpowers #18. However, his stamina soon wears out and he's defeated, whilst present Gohan is unable to handle both #17 and #18. The two leave as in canon and request that the Gohans fight them again sometime.
With Dende having learned all he can from Kami over the 4 years and being the new Grand Namekian, he uses the Dragon Balls he inherited to summon Porunga and revive Goku. It's then that Piccolo and Kami fuse, with Dende taking up the mantle of Kami and placing his power in the Shenron statue too as an additional precaution. Cell shows up in Gingertown and things go as in canon. With how things went down, Goku then brings up going in the Rosat, choosing to go in with Future Gohan whilst Piccolo and present Gohan search for Cell. They are never able to find him, whilst Cell likewise cannot find #17 and #18 due to them not really doing much. Once Cell is confident in his power, he starts destroying whole areas to lure the twins out, which is eventually successful. He quickly absorbs the two before Piccolo or Gohan can do anything and becomes perfect. Whilst attempting to kill them, he asks what Goku is doing, to which he's told that he's training to defeat Cell and, thus, the idea for the Cell Game still occurs. After emerging from the Rosat and resting a few days, Goku then goes in again with present Gohan to give him the same training whilst Piccolo goes in between then.
When the Cell Games occur, Goku goes first and eventually gives up, with Future Gohan taking over. To everyone's surprise, he then displays a new form - Super Saiyan 2. Having already been accustomed to Super Saiyan, mastering the form took less time and Goku had more time to focus on developing Gohan going further by utilising his rage fully. Gohan wastes no time in killing Cell before he can even think about self-destructing, quickly ending the fight. Cell's victims are then revived, Gohan returns to his future and peace is restored.
The Boo Arc starts off in much the same way, though Trunks' absence makes Goten significantly weaker and the champion of the kids' division by default. Things then go the same up to Babidi's spaceship in which Piccolo takes Vegeta's place. That also includes being turned into a Majin, though his vastly inferior power means he doesn't become a major threat. Whilst Gohan chooses to oppose and reason with Piccolo, Goku quickly kills Dabura and Babidi, bringing a swift end to the arc.
Without Vegeta or Trunks, the God ritual can't be performed when Beerus shows up. This leads to two possibilities:
A - The God ritual isn't peformed and Freeza destroys Earth months later.
B - The Dragon Balls are used to bring every surviving Saiyan to Earth, with Tarble, Paragus and Broly taking Vegeta, Trunks and Pan's places. However, Freeza still wins months later as nobody is powerful enough to oppose him after Goku is caught off-guard, nor able to provide Goku a senzu without Freeza stopping them.
In both scenarios, Zamasu's Zero Mortal Plan never takes place, leaving Future Gohan's timeline unaffected.
Scenario 2 - Nothing would change, honestly. If Bulma was willing to end up in a relationship with someone who was responsible for her ex's death, I doubt she'd feel any different about him killing someone she knew for a few minutes at best. How she felt in the moment wouldn't matter when such a short memory would soon fade.
