1. When stainless is cut with a plasma cutter, does it cause any discoloration in the metal?
A. Yes

2. Can the stainless be finished somehow after cutting this way?
A. I'd suggest sand blasting then powder coating rather than natural stainless finish. Try to pick flat non-reflective colors the same as the environment it's mounted near for camo.

3. I was looking at the Hypertherm 1250 for a cutter. Could anyone comment on it as being a reasonable choice?
A..I like my Hypertherm.

Rather than make a huge investment in equipment, not to mention learning curve, why not sub out the plasma profiling and bending? I have a good low cost source for both in Virginia. Great turnaround time too, usually next day, three at latest. His plasma cutter cost around $79K with very large table and 200+ amp output, also has two oxy-fuel heads.

Couple more items you might need:
Air compressor for the plasma machine, air powered tooling like die grinders.
Free standing belt/disk sander
Electric angle grinder
Manual mill/drill with vise, clamps and tooling.