Hi, I used to have a Cougar it was ace, wish I still had it!
If you have Nicads and a brushed motor these will be fine to get yourself or your son back into it. I recently got a nicad out of a cupboard it had been stored for over 10 years and still charges and discharges fine. I know that as my charger tells me how much is going in and out. That's one thing you will like, modern chargers are the business.
Brushless motors do not have brushes or a commutator and so do not have the associated friction and heat.
Lipo batterys are better but you really don't need to worry about any of this you can run what you have for a while no probs.
