What ship will you be sailing? Some ships are better designed to handle strollers, etc. On some ships, full size strollers are not advised only because they don't fit through the doorways. I realize spending money on another stroller may not be in your budget, but I know that Kelty makes a great stroller that converts into a backpack - super for cruising!
Can't help you much with packing tips, since it has been a long time since my daughter was an infant, but here is a link that might help:
Also, if I may make one suggeastion - definitely budget money for the in-cabin babysitting service available. The $5 per hour could not be better spent, if you are not traveling with grand parents or an older sibling/relative to allow you some adult time.