Well first you definitely need to talk to Jake and figure out exactly how he feels. If he's gay, it looks like you guys have a relationship in the making- though be careful, as you don't want to mess up your friendship. If he's not gay, I personally don't believe in friends with benefits, but that's for you two to deciede.
As for Zach, I think you should just keep your current relationship going with him, at least until you figure out what's going on with Jake.
Hope this helps!