I started a thread that I think that you might be interested in, it sort of covers many of the "what ifs" that you have and I think you would enjoy reading the comments.
-- Edward's reaction to a Jacob/Bella…"
"I don't think Bella would have gone with Jacob because the moment the phone rang although she was thinking about it she still hadn't decided. There other near kiss also happened AFTER she jumps (I think) so she still would have run of to…"
"Ok with your added information. I do not think that a few months would have made much of a difference (especially with Bella knowing that Edward was back). I think that it would take years of Edward being away and Jacob and Bella being married (I do…"
"I think Jacob would eventually leave Bella. I think after time, it would bother him to know he couldn't have her whole heart.
I think his age plays a big part. He is still so young and as time passes it changes us & our feelings for people.…"
"Well, he said he that he would probably have come back anyway because he loves her and can't live without her. So I think he would probably come see her and she would probably be hyperventaliting. And then Jacob would come..... Well, I would…"