C is also used to designate how many cells are in a nimh or nicad pack.

So a 7C 600mah nimh pack would have 7 batteries in it.

For some reason, 'S' is used for Lipos. Not sure why....

As for your second statement, that is the direction lipo's are going. It seems most of them come with a second connector (called taps) which are used to charge the battery. These taps allow the user to charge one cell at a time (or all at the same time if you are using a balancer or multiple chargers) so the pack remains balanced.

When dealing with nimhs or nicads, apparently a slow discharge/charge cycle every now and again will keep those packs balanced.