If you're in >200ft of water, you can heave-to or put out a sea anchor to reduce drift. Look up sea anchor or parachute sea anchor. There are a few other things you can do to reduce drift as well. In other words, yes it's possible to almost stop a boat while at sea.
As far as clearing customs goes, check with your country's officials before you leave (get all required paperwork). When you arrive at a new country's port, fly the "Q" flag (a yellow flag). This lets customs officials know you haven't cleared yet. Yes, you can expect to pay some fees...but may get lucky depending upon the country.
Financing a boat is up to you. Some people get loans, some pay cash. Depending upon your state's laws (& how crafty you are

), you can expect to pay sales tax (10% +an arm, +a leg

). Don't forget you may also pay additional taxes depending upon your county and city.
Hope I helped,
Skipper, J/36 "Zero Tolerance"