I hear you on the Cali sales tax! I just moved out here and had to stop buying from AMain as well. I love their prices and shipping, but simply cant aford to tack an extra 30.00+ on an order already over 200. I had to switch to Tower, they do just as good for shipping and their prices are only as dollar or two higher on avg. By the time it is all over Tower turns out to be a few bucks cheaper, really a shame IMO.
+1 on the Elite RC mount, that said the stock one does work just fine if you plan on using just one pinion, setting the mesh and forgetting about it.
After experimenting with different pinions on different tracks, the Elite is a dream to work with!
Your right there are a million batteries to choose from. I also bought a couple 4S hardcase jobs from hobby king and they work great as well and I think I paid 80.00 for two!