questions about Race Wheels

that's kinda depends on your goals and other factors.  Are they faster than youre Ksyriums? yup - http://www.rouesartisanales.com/article-15505311.html

Youll need shimano compatible.  SRAM is shimano compatible

I do, but I just got my set in this past month.  though, I have friends that train on their race wheels.

I hear H3s are bomb-proof

More of a personal preference now, but clincher for me.

There are some places that do a rent-to-own type of thing.  You rent some wheels and you can apply some of the cost to rent them to new wheels. I think racedaywheels.com and echappeonline.com do that.

Are they really worth the cost? Only you can determine that.
I have SRAM components. How do I know if the wheels are compatible? SRAM and Shimano are compatible.
Do you only ride the race wheels during races? Do you have 2 sets of wheels - One for training, one for racing?  That's what I do.
Is there a good quality versatile wheel that is good for both training and racing? For me, I don't want to waste my race wheels in training, and I prefer to train "heavy" aerodynamically speaking. So to my mind, there is no good versatile wheel for both training and racing.
Clincher or tubular? I use clincher, because that's just what I'm used to.
How about the race day rental option? Any thoughts? Never done it, but a lot of people have with great results.
What else do I need to know? I might try some wheels off of ebay so I'd want to be knowledgable. Are used ok? Used anything is fine as long as you know what you're looking at and feel like you're getting a good deal.

Very hard to justify dropping 2 grand if I'm only racing 3x/year. Then I guess that's your answer to #1...

What Briderdt said.

Plus: How fast are you? If you can't average around 25mph in a 40k you may not see any results at all. Slower than that you will get more bang for your buck with an aero position and an aero helmet. But hey, you'll have cool looking wheels you use 3x a year!

I'm thinking about race wheels as well, just contacted the people over at echappeonline.com and have to say I was impressed.  They were willing to get a set of wheels in for me that they wouldn't usually carry (HED JetC260 EX's) and emailed me back within 30 minutes of me emailing them.  It's tempting, that is for sure. 

If you're moving forward, you're getting some aero benefit.  There's no magical speed barrier.

^^^ What he said. In fact the data says that when you're slower, the actualy time gained (in raw seconds) is greater than for a faster person.

Others are more qualified to answer your questions but for some back up rental info. since you only race 3x a year.

I rent for $75 a weekend.  (If I choose to buy...they will deduct the price for the season)

At IM CDA Zipp was there and renting on site for I think $125-140 somewhere in that range.  Then you don't have to worry about taking two sets of wheels.

Note:  If you rent make sure you pick up a couple of spare tubes that fit the race wheels and have long enough stems on them just in case.

Carbon or Aluminum for the H3's if I am going to use them everday + raceday?

Does clincher vs tubular make a difference to you? 

Want to stick with Clinchers.

Edited to add, I see they don't sell Carbon clinchers on their site but..

http://cgi.ebay.com/Hed-3-Front-Carbon-700c-Clincher-Tri-Spoke-BRAND-NEW_W0QQitemZ320290875537QQcmdZViewItem?hash=item320290875537&_trkparms=72%3A552%7C39%3A1%7C66%3A2%7C65%3A12%7C240%3A1318&_trksid=p3286.c0.m14

are these not really carbon?  or not really clinchers?

They are carbon wheels, but the rim is aluminum. They only make the clincher in an aluminum rim/braking surface.

ETA: To my limited knowledge, they only make the clincher in an aluminum rim/braking surface. 

aah, ok.

So what is the real diff between aluminum rim and carbon rim other than needing new brakepads?

Any advantage?

I believe the full carbon rim will be lighter.  It also changes your tire selection, obviously.  Beyond that, someone more knowledgeable is going to have to help out.  

For training and racing, an option is something like the new TTR2 Felt 40mm Al clinchers (650 shown)?  They're available on the DA and the B2, with the TTR3 on the B12.  I've been watching several of these wheelsets go on Ebay for $400-600.  Superdave (from Felt) said retail is $700 or so.