Ajari...there are other threads on this so you might do a search for more but...
1. Huge aft cabin & PRIVACY
2. All around visibility...easier close quarters handling due to mid-ship position.
3. Ability to fully enclose cockpit without loss of visibility.
4. aft deck space for storage of bycyicles, life refts etc. without impairing visibiity or access to foredeck.
5. Dryer as it is harder to get pooped by a wave into the cockpit and since you are also higher.
6. Easier motion in the cockpit since you are not hobby horsing at the end of the boat.
1.Less on deck locker space due to use of space below deck for aft cabin.
2. Harder to dock since you cannot reach from the wheel to a piling.
3. Ugly condo look if not done right...generally over 40' is required. Excess windage on some boats.
4. Sometimes poor ventilation in master cabin if blocked by cockpit.
To answer your other questions:
1. Cockpit is drained by scuppers and hoses led down through the hulljust like most aft cockpit boats . More and bigger is better.
2. There is usually an emegency tiller fitting through the aft deck plate above the quadrant and a 2 piece emergency tiller that fits this opening and then runs forward. Sometimes it is quite klunky!! I like to think of my blow deck autopilot as my emergency tiller since it can steer the boat if the wheel system fails...and my real emergency tiller is my 3rd backup.
3. Cockpit noise has never been a problem...you still have a v-berth as a choice anyway.
4. Getting aboard is not an issue unique to CC boats...our BEST boat for getting aboard was our Irwin 44CC which had a motorized drop-down dive [latform which was great for off loading heavy stuff like groceries or laundry from the dink.
Having owned both types of boats, I am a confirmed CC guy for living aboard especially since I am tall and the aft cabin lets me stretch out.