Ceiling paint (in most cases) is flat and covers in one coat. Use a non-water-based product for unsealed stucco or ceilings subject to smoking stains.
Trim paint (doors, baseboards) use melamine, pearl, or semi-gloss for resistance to animal oils, wet mops and vacuum cleaners.
Walls need a fully washable paint. Interior paint dries in 4-6 hours and can be re-coated In the same day. Two coats are recommended if it is possible to see the previous colour or flashing. If going over primer you must do 2 coats (unless you are using flat paint). Some colours require multiple coats particularly yellow and reds. White primer is recommended for yellows. Gray primer for reds.