You dont need new calipers unless they are sticking and not releasing right. I have had good luck with bendix replacements myself though.

As for the idler arm I got a cardone iirc, but any major one should be fine like beck arnley, etc.

As for drums, unless you have ALOT of miles the insides of the drums shouldnt be rusted-if they are or they arent within spec I suggest bendix again, thats what i replaced mine with. Of course the outside rusted but the insides ok.

1996 T100, Mickey Thomson Classics, Bridgestone Dueler AT 265/75/16, custom offroad KC's.