3 stash tabs leaves you 1350g, which would be enough for 1, 2, or 3 heroes. Or you could do 2 stash tabs and pick up an extra 450 hero and have 50g left.
As far as who to pick, you have a reasonably tanky dude in the form of Cap, and a strong AE in the form of Storm, and Spidey doesn't suck...