First, you don't need carbon at all. The space is better used for more biomedia. Filters need to be cleaned more often than every two months.. it depends on the media, fish load and filter type, but at least once a month, maybe once every 2 - 3 weeks. Carbon doesn't release things back into water, btw, that's a bit of a myth, but unless you have medication or nasty odours or colour to remove from water it's just not needed and in some fish, may actually be detrimental.
Water changes, well, technically you can't do too much, so long as the water you use matches in temperature and other qualities. Be sure to use a good quality dechlorinator.. Prime is one of the best and quite economical, as you use very little of it. The usual is to change maybe 25-30% weekly, but more or less may also be fine. If you have plants, often you can do less, as plants use up the nitrates.
Get a test kit, you will need it anyway to be sure of the cycle, and that will tell you when nitrates are getting to the point you need to change water. You need to test for pH, Ammonia, Nitrite and Nitrate. You may or may not need a heater. It depends what fish you choose to keep and how warm the room is where the tank will be. Check the needs of the fish you hope to have, that should tell you if a heater is needed. I haven't ever needed any, but I keep mainly cooler water species, rather than very tropical species.
Most fish enjoy clean water, so having a more intensive water change schedule is not a bad thing in any way. It can get to be a fair bit of work though.