1) How long does it take from Santo Domingo to Puerto Plata by bus? how much?
About 31/2 to 4 hours
2) How much is a taxi from Bus Station in Puerto Plata to Hilton Coral Marien?
Should be very inexpensive if you get a public taxi.
3) How much is a taxi from POP airport to Hilton Coral Marien?
About 20US
4) Does Coral Marien has a free shuttle from airport to hotel?
Don't know.
5) How long from Sto DOmingo to Santiago by bus?
2 hours
6) How long from Santiago to Pto. Plata by bus?
1 hour maybe more depending on traffic7) How much is a taxi ride from Santiago bus station to Coral Marien? how long?
Don't know.
If you fly into SDQ take the Caribe Tours bus. You need to take a taxi from the airport to the bus terminal. You will probably save money flying into SDQ. POP is always more expensive unless you get one of those AA deals. Here's the link to the bus company.
http://www.caribetours.com.do/