No reason you shouldnt be able to purchase tags and lic online , you would need a reduced bear tag , you can get two for unit 12, you can as Rick stated just pickup over the counter when you get to Idaho.
As far as baiting , you will have trouble just minimal baiting in unit 12 as the is lots of access and lots of others baiting hard in that unit, you will be competing with them, but hey , you never know till you try right?
You may want to avoid your buddies baits as beaver is not legal to use as bait in Idaho as its a protected non game species. See regs under baiting and bait.