Confirming RWD 16v parts will work on 20v blacktop with some alterations. The alternator bracket needs some grinding to clear a rib on the block near the dipstick. There was some slight clearance problem with the PS pump that required shaving the plastic cam gear cover a tad and shoving it all the way to the left. I am using the 16v PS pump and it works fine.
I'm not sure about AC because I removed mine, but the bracket fits.
The 16v crank pully is used but probably needs to be shaved on the back depending on what specific version of 20v you have. I belive AE111 all requre it. There is a post in a sticky thread somewhere that has a method to fix the problem using a timing gear from a diffrent engine, but I decided to KISS and use a shaved pulley.
To sort the crank pulley out, check out the section "Toyota Front Pulley" on the page here:
I have no idea about the FWD kit, except to say that I've been told by a pulley vendor that FWD/MR 4AGEs have belts closer to the engine, so probably can't mix/match FWD/RWD accesories.