I'm new to the AR15 but not new to rifles.

I've found that the combination of the right cleaning solvents and plastic bore brushes and patch pullers can clean the insides of a chrome-lined VEPR of all lacquer/carbon/gunk in under 5 minutes.

I plan to use the same strategy for the AR15 except without the use of ammonia (due to the aluminum receiver and possible use of aluminum in other parts of the rifle)...

I am going to get a 24" barrel .223 AR15 upper, what length cleaning rod will I need? 36"?

I will have an A2 flash hider, what type of bore guide will I need?

I will be using CLP and Militec-1 (as I have for my VEPR)

I'm not real sure about the length of the cleaning rod, but I would definitely get a chamber rod guide rather than a muzzle guide....ALWAYS better to clean from the chamber end.  I bought one from  Georgia Precision and I think it's top notch (no pun(s) intended).

http://www.georgiaprecision.com/cart/images/AR10%20BORE%20GUIDE%201.jpg