Re: Simplest Rackmount rig
I've built a few racks over the years and if you're looking for simple and/or cheap you should forget about racks and look elsewhere. If you're OK with the complication, expense, and weight here's what I'd recommend for a basic rack / effects system.
Preamp: ADA MP-1 or Marshall JMP-1
The Marshall is more expensive, but it may still be possible to fix if something goes wrong. The ADA has a really cool 'Jazz Chorus' solid state clean that you can't really find anywhere else. Its major downside is that your preamp becomes a paperweight if anything goes wrong.
FX: TC G-Major
Original G-Majors can be had for $150 or so. The modulations aren't amazing, but the reverbs & delays are excellent for a unit so inexpensive.
Power: Peavey Classic 50/50 or 60/60
It's true that Mesa power amps are better, but you can't beat Peavey for price, decent tone, & reliability. I'd stay away from Marshall stuff as their build quality just doesn't justify their prices.
Control: ADA MC-1 (simple / cheap) / Rolls Midi Buddy, ART X-15 / Behringer BCB-1010, or Rocktron Midimate / Voodoo Lab Ground Control Pro
The MC-1 and Midi Buddy are about as simple as midi controllers get. No expression pedals or inputs, and it sends a single program change per button press. The pros are that they're dead simple to use as there is literally nothing to program. The downside is that there isn't much flexibility. The other end of the spectrum is the Ground Control Pro. Expression pedal inputs as well as programmable buttons that can send several program and control changes at once. A bit daunting a first, but one of the easiest pieces of gear I've seen to program. They run about $150-200 used so about 3x as much as an MC-1, though not horrible. I've also heard decent feedback on the ART X-15 and Behringer BCB-1010, though I've never used either.
I couldn't tell you on wireless since I don't use one. I personally don't care for their effect on the guitar's tone & feel and just use a cable.
These are just the basics to get started. Keep in mind that you'd also need a rack case, power distribution, and a couple of cabinets since a system like this is best run in stereo.