As for the shuttle the resort does offer one. I spoke with the front desk a few weeks ago and they said it was $220 US/person for a round trip transfer to and from the Punta Cana airport. Is that where you are flying into? Since you have a whole group you should probably be able to negotiate something cheaper. For my group we booked the all inclusive trip so it's included. Did you just book your air and hotel separately? If not you may already have transfers included I world check with your TA. As for room assignment that is usually done through your TA. Also you could email/call the concierge. Iâ€™ve asked Tiara about this before and she said she couldnâ€™t do anything.
Hope this help!