1) Yes, once you enter and get your copr signed, you're good for 5 years.
2a) You cannot give your friend's address without claiming that you'll be living there.
2b) Since you have to claim that you'll be living there for step 2a , this would be a problem.
3) Yeah, with your signed Copr and passport, you can enter by private vehicle or by foot. You can sail in your own boat from Europe if you like. PRTD could take several months.
I recommend that you don't apply for the card during your initial landing and just pay for it later.