Be careful with the brass polish
Some great ideas for cleaning there but be careful which brass polish you use, Unless you use a brass polish specifically made for tumbling shell cases it will probably contain ammonia! Ammonia causes the brass to become very brittle and will cause the cases to fail prematurely.
Brasso and most common cleaners contain ammonia so dont be tempted to use them, Instead look at Midway or one of the other bug suppliers and buy the right stuff.
As far as time in the vibratory cleaner, I leave then in till they are clean, some times as long as 12 to 14 hours for range pick up brass that has really discolored.
Have fun
Roger