Well youd want 2 gigs of ram, something like a X850 and a P4 3ghz+ for a smooth experiance.
Physics are the best there is as far as fighter jets go. You really feel like you got an aircraft under you.
Only flyables are Su-27, Su-33, Mig-29A/C, F15, A10, Su-25/T. As far as hardcore sims go it doesnt get better then this

Usualy all you get is 1 aircraft. Here you got 6 models. Unmatched before
Avionics depends. For the Su-25T(Flaming Cliffs Addon) they are fairly involved.
For the rest its nothing but easy. I mean you still have to operate everything, work the different radar modes, manualy work the radar azimuth, work the optical scanners etc...
The upcoming Ka-50 addon will however be hardcore down to every single switch in the cockpit. Engine start up procedure is going to take about 15min alone

You have to flick every switch in the same sequnece as in real life.
Yes you can inflight refuel.
It does take a long time to learn

If you want to be good you have to study every weapon, different missle evasion techniques, the trick of the trade, how to work the radar to your best advantage, how to launch a weapon on a jaming enemy.....many things....
I personaly only know how to fly the Mig-29 and the Su-27, and I dunon the Mig-29 that well. I dunno fuck all about flying the F15, or how to work it.....stupid western avionics......I a steam gauge guy
To get an idea of the avionics etc check out the manual, I uploaded it here.
http://www.is-mad.com/upload/userfil...LOMAC_manual_1[1].1.rar
Sure you can fly the F14 but it would just be the 3d model

and it would use an F15 model for base.
You can download other aircraft, but once again their physics avionics will be from one of the other 6 models. Anyway, how many at home people have access to enough data to even loosely simulate a fighter jet
Everthing is modeled fairly intensly. I mean each missles seaker head is modeled, up to a point where its not classified...thats when they have to guess. For example whats the scan interval of the AIM-120s scanner

But they can still get very close to the real thing...