The entry point to the EU would depend upon flights available from POP. They are limited. During a trip I would like to go to three different countries.
Yes, Poland is one of the three countries so I can visit a cousin. Spain is the other main country where my wife has a cousin. If Paris isn't easy, then I would leave France out.
Yes with respect to the visa needed.
https://www.schengenvisainfo.com/schengen-area/
No idea on that and I hope that does not play into my trip. I live on the north coast and don't wish to add two additional days to my trip going to Santo Domingo. and back. I hate going there anyway. I would much prefer POP to the EU and back to POP. I have not yet checked on any flights. We could also connect through Miami or JFK, but then that adds potential layovers. Anything else?