You will provide your cruise line your flight departure time. They do assign disembarkation times and your departure time is one of the factors in that equation.
Most ofter self service - but then you have to lug your own bags. Some people love it, others avoid it.
A Bad Day At Sea [with power] Always Beats A Good Day At Work
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, 2014, Caribbean 2013, Coral 2014