Personally on your first cruise I would get an outside cabin. You certainly don't need a balcony on a 3 nighter, and it's a bit more of an experience than having an inside cabin. You'll have a fab time.
Yes to all of those. You will only need money when you are ashore, on ship it's a cashless system and anything you spend will be on your credit card bill at the end of the cruise. So it depends what you are doing ashore really, how much money you will need.
Right, I've decided I want to take DS on a cruise. He'll be 8 by the time we go. It'll be a 3 night cruise to Paris/ Bruges.
What do I need to know? Will it work if it is just the 2 of us? Can he go to a kid's club for some or all of the day (depending on what he wants to do)? Can I lounge somewhere & read books? Is food included? How much spending money will we need?