I've always been sceptical that Bill will appear in L&T, and I'm doubtful that any possible vendetta he might have towards Gamora and Nebula is going to play into this movie.
Besides, why would Thor go out of his way to save Gamora and Nebula anyway? He barely knows either of them.
But I do think this could potentially be a cool way to introduce Bill at a later date (possibly in GOTG 3). Maybe he fled Korbin when it was under attack and ended up on Sakaar - hence the sculpture of him?
And as for him getting Stormbreaker, I think the MCU version of Stormbreaker has been pretty clearly established as Thor's weapon at this point. And with Jane getting Mjolnir, what's Thor supposed to fight with, anyway? His fists, again? I've always felt that there's a danger in making too many characters "worthy". We've already had Thor, Odin, Hela, Vision, Cap and now Jane. If they introduce yet another worthy, hammer-wielding character in the very same movie that they're portraying Jane as worthy for the first time, it's going to cheapen the whole idea of worthiness.
If everyone can lift Mjolnir and have the powers of Thor, then what's the point of Thor himself?