Yes, they do. Almost every "job" you would see in a city, they have on a carrier.
Yes, but not easily. What you score on the ASVAB will determine which jobs would be offered to you. This is a critical choice as you cant change your mind once you start. However, you can join the Navy as what the call "unrated". What that means is the will train you in the general skill of either: Airman, Seaman or Fireman. Thats not as cut and dry as it sounds as each of the three general categories I just listed have many sub-categories. For example, I joined as an unrated Airman and my first job was AO (Aviation Ordinance) and I spent my days practicing assebling missiles and bombs. Later I decided to become an AE (Aviation Electrician). So think of it like this; an Airman will do some aircraft related job, a Seaman will do some shipboard related job and Firemen will do some damage control related job. The down side to that path is you dont get a choice, when you arrive at your first duty station they will stick you wherever they need you, within your field.
Zero. You dont have any expenses in the military at all. Well besides the hookers and booze.
Medical, dental, food, lodging, clothes, haircuts, etc... all paid for. I actually had a lot more liquid cash while I was enlisted because my only expense was my hedonism.