Totally Newbie Wheel Question

1.  Yes. They will get you at least 95% of the aero benefit of a regular disk wheel for a fraction of the cost.

2.  Their site doesn't explicitly state that your bike or wheels are incompatible (though it does mention the Kestral 4000TT).  

Read the full list of exceptions here: http://www.wheelbuilder.com/aerodisc-troubleshoot.html

To check on your own, as they state on the Aero Disc home page

Your wheel must have at least 5mm of clearance between the largest cog on your cassette and the drive-side spokes.

1.) Yes.  As for exact "numbers" I don't have them off the top of my head.  It adds a bit of weight (just under a pound) which could potentially slow you down on a really hilly course, but in general, they are a great cheap way to drop your bike split.  I would personally buy one if it weren't for the fact that they won't fit my stock wheels (shimano r500)

2.) I am not sure about this.  Your best best is to email Wheelbuilder, they would know for sure and I hear they are really helpful.

The Talon should be fine.  The issue with the Kestrel 4000 is on the non-drive side where the Wheelbuilder cover flares out too much.  The chain stays on the 4000 are very tight to the wheel and that non-drive side is a no-go (the drive side is fine).  I had to make my own cover for that side with my 4000.  On my old Talon I just taped those suckers on and rode off.