Oy... here we go...
Can't speak to the long-term durability of a carbon frame. If you buy a major brand, just be sure to register it with the maker, and then you'll be fine no matter what.
As to maintenance, it's normal to do a 30-day tuneup on a new bike to compensate for cable stretch and bearings breaking in etc. That's usually included for free.
A further note on durability... bought my bike used, with a factory mix of Tiagra and 105. So, not a high-end groupset.
Near as I can tell the previous owner had ridden the bike enough to require a cassette replacement, or maybe he just did one when he replaced the rear wheel. At any rate- my bike had been ridden, and by a Clyde. Since buying it I have... uh... oiled it, put new brake pads on it, and replaced a chain. The chain wasn't even misbehaving; it just tested as stretched on the gauge at the LBS. I have put about 2000 miles on it this summer and I'm over 200 lbs and climb hard a lot. Not easy miles, for the bike. It shifts fine, brakes fine, and rolls fine.
A new higher-end bike will be very low-maintenance and the durability of the groupset (I WILL NOT say gruppo!) will astound you. As to the frame... ride that bee-atch hard and HOPE the frame asplodes... that way you get a new frame!
Good luck in whatever route you take.