A. Not necessarily. The formal nights are a big part of the fun, but don't buy a tuxedo just for that. A dark suit is perfectly fine. If you do want to wear a tuxedo, then you may bring your own or rent one on board the ship. There is usually a form to fill out and send in ahead of time, so that your tux will be waiting for you in your cabin.
Cruises are ideal for singles because it is so easy to meet people.
In most cases, ships have single cabins or single rates for a double occupancy cabin. There is also the choice of the cruise line finding you a roommate to share the cabin if you ask for it. There are certain age restrictions. On most ships, no guest under the age of 21 will be booked in a cabin unless accompanied by an adult 25 years of age or older. In some cases, the minimum age is 18.