Does anyone know of a good resource to help in reloading for my AR-15 in 5.56? I've got a lot of questions such as "how to get near mil-spec loads" and "do I need to crimp?"

Try here

AR15 Armory.com

and

Here

AR-15 - AR15.COM

And

Here

Hard Data on 5.56 vs .223 Chamber Pressures « Vuurwapen Blog

"NEEDING" to crimp is more about HOW your rifle feeds, and your case prep. In the 7 AR's I've had, it was never necessary.
"MIL-SPEC" isn't what you think it is, or hasn't always been at least.

The few army Tech manuals I have, and the history of Ohlin/Rem/Federal deveoping with the Army doesn't HAVE the average operating pressure really any different than the 223. The 5.56 is allowed individual cartridge pressures to be 60,000psi, but the average is 55,000psi.