Whew...quite a few questions packed into one post!
The DL MD-88 going from ATL to JAN would most likely have at least two, full-size liquor carts boarded, one for FC and one for YC. I don't think there are any majors who use 1/2 size carts (ERJ/CRJ style).
Takeoff can be tricky. Due to some restrictions imposed by the regulatory authorities, as well as design restrictions, it will be rare to see a full size galley with only one cart boarded. Often times, catering will also board a few empty carts next to the cart being used just to deal with these restrictions. Looking at certain areas in the galley, there are placards which say "all or no carts must be boarded"...but, it varies greatly with the configuration of the galleys that the airlines have.
Different carts are used on different airplanes, just for the sake of effeciency (so no, an aircraft doesn't keep the same carts). Once a cart is taken off the plane, it is unloaded back at the catering facility, thoroughly washed and sanitized, and then loaded with food/beverage for the next flight. Very effecient.
Not all commuters and low fare carriers use tiny beverage carts. I believe that only the commuters (SkyWest, Mesa, ASA, etc.) use the 1/2 carts. Carriers like Delta Express, Metrojet, Vanguard would definitly use a full size liquor cart, if not have specially-built galleys which have no carts...just bulk-boarded beverages in a sort of 'pantry' if you will.
Any more questions just ask!
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