Welcome to the madness, Lane!
Before I start, many will suggest that you first look for a used one. I don't know how many would be available with the options you want, but you could very well save money that way.
Under $30k is a pretty broad range actually, if you're willing to build the car yourself. If you want to find one with all the options you want, already built, your choices may be non-existent. You definitely won't find a newly built car with a new engine under $30k. Such an option does not exist. Pretty much the only way to get a built Cobra replica under $30k is with a used drivetrain or used altogether.
1) I couldn't possibly bring myself to putting A/C in a Cobra. Nor a stereo for that matter.
I would imagine PS and A/C can be fairly easily added for any car that employs the single-donor concept, and the electronics, smog, PS, and A/C systems out of the donor car could be used. How well it works is not a question I can answer.
2) I think any Cobra could be made with undercar exhaust. It's quieter and you won't burn your leg, but everything else is a negative in my book. Come to think of it, why would you want a quiet Cobra?
3) For a street car, I would think EFI is a no-brainer. If originality is more important to you than dependability, go with carb.
4) I'm not qualified to answer, but I would think IRS would make for a nicer ride quality but maybe not $2k nicer. If you're not putting a ton of horsepower in it, you shouldn't have a problem either way mechanically.
5) As far as I can tell, the main difference between the FFR frame and that of most other makers is the 'birdcage' of perimeter rails for attaching the panels and body. The RUCC has heavy-gauge beams in the doors. What else makes them different from the rest? What does 'tube' have to do with it? They're all made out of tubes! What is the 'backbone' of an FFR frame? As far as safety goes, is it better to have 'crumple' beams that are not so large, to absorb energy? What about the structure around the gas tank? I think it's a good idea to have solid beams surrounding the cockpit to prevent side-intrusion, but this is extra weight. Still, all-in-all, if safety is your first concern you should not buy a Cobra! Safe is relative term...
6) Most (if not all) makers offer dropped footboxes which adds more room. My maker (Carcepts, Pacific Roadsters) has a recessed rear firewall which adds cockpit room. I would think a 6' 185lbs driver would fit fine in most Cobra replicas.
8) Have you tried Hunter? They're in Florida.
I think for most of the manufacturers you list, you could only get a car for under $30k with a used drivetrain. If you build it yourself, an FFR could probably be built with the weather components and a new drivetrain.
I also fall under the $30k price limit, and I ordered a complete turnkey from
Carcepts/Pacific Roadsters in Salem, Oregon. This is a complete car with soft top, wipers, paint, premium wheels, original-style interior, 5-point harnesses, Autometer gauges, coil-overs all around, and ceramic-coated exhaust, with EFI drivetrain (rebuilt T5), solid-axle rear (3.55 gear upgrade), gas tank, radiator, etc from a 108,000 mile '93 Mustang. My total cost is $26k. Power steering was optional, and I'm sure Kraig can do A/C too. For $30k you could substitute a new engine I imagine.
Good luck!