Regarding Jane's death. The way I saw it is that Walt wanted to save Jesse from continuing his junkie ways and he saw Jane as bad influence on him so he decided it's best if she'd die so he could take care of Jesse.
To him Jesse was like his family member, like a son he can share his criminal side with. Don't believe that he wanted Jane dead just so Jesse could cook with him again.
Regarding, "they would've figured it out where the money is anyway". Most likely, still why help them and lose the leverage when by not saying it you get the chance of them not figuring it out.
I'm not so sure if Walt comes back in the end to save Jesse. I was thinking what'd be interesting is if they made us believe so, and then he'd just come back just for revenge and kill Jesse too.


