Other equipment - Coleman sleeping bags are OK. Add 10F to the temp rating to get a better idea of how comforatable you'll be. I went to a surplus Military Sleep System for myself. It's heavier than the high end gear, but the whole set (warm weather bag, cold weather bag, bivy cover, and compression sack) can be put together for around $100 by keeping an eye on Uncle Sam's Retail Outlet or hitting up Old Grouch.
A three burner Coleman propane stove is hard to beat for car camping. If you're planning to backpack much, then you'll appreciate an isobutane stove from MSR or Snow Peak, a woodburning stove like the Emberlit, or an alcohol stove like the Trangia. BSA does not allow Scouts to make their own coke can or "penny" stove. One benefit of having a stove is typically you can still cook when there's a burn ban in effect (no open flames).
Cub Scouts are not allowed to carry a fixed blade knife, so look for a Swiss Army Knife if you think he's mature enough. I found an actual Cub Scout edition SAK at a gun show for $15.
Get him a Camelbak - they sell Cub Scout themed ones at your local Scout store or you can find the kid sized ones at most places you find Camelbaks for sale. This gets them used to drinking lots of water.
Build your son a basic survival kit - a few bandaids and a whistle to start with, flashlight, maybe a space blanket, add firemaking stuff when you think they're ready. Keep it simple and go over the pieces with them. Mine likes to play with the whistle while we hike, which I don't mind, but I do remind him that three blasts means "HELP!" and to not do that unless he really needs it.
Another fun project I'm setting up for our den is making survival bracelets. SupplyCaptain.com has plastic buckles with whistles built in and any color cord you could want. I bought Neon Yellow with reflective markers and Navy Blue 550 cord for them. When they're done, they'll have a little less than 10 feet of cordage and a whistle with the added benefit of something reflective if they're out at night.
It's also an unwritten law that you must the makings for smores whenever you go out! They seem to put with alot of "suffering" if you give them chocolate and sugar afterwards!