Yes, there is an AOA system. In the F-15, we actually fly nearly EVERYTHING in reference to AOA instead of airspeed. For maneuvering flight, it's obvious why we would want to use AOA, since that is the true measure of a wing's performance regardless of airspeed or aircraft weight.
Here's a shot of an Eagle HUD; you can see the AOA under the airspeed on the left center of the HUD (it's the number after the '
a' symbol).
Here you see just under 30 units of AOA being pulled in this turn to gun whatever sorry bastard is under the gun pipper. 30 units is considered our "best turn rate", but it generally results in a loss of airspeed.
The F-15 doesn't display actual degrees of AOA, but an arbitrary unit of measure called "cockpit units". If I recall right, if you subtract 10 or so from the cockpit unit readout that approximates the actual degrees.
The "stall warning system" does not exist in the Eagle. We fly it down to speeds well below what any normal pilot would consider a "stall", literally standing the jet on the afterburners and using Newton's laws against the belly of the jet to keep us airborne. Slow speed dogfights take place 50 or so knots below the level flight stall speed.