we got a cabana in April. It's $100 with table/4 chairs and then 4 loungers in front. You email and give CC and then they charge it upon arrival. They have your name on a list. I thought it was worth it. There is no need to buy food/drinks if you don't want to. They also have cabanas surrouding an adults only pool with curved booth type seating. Those are the ones with $50 minimum purchase. You can also just rent umbrella/chairs closer to the beach, but if you have 6 persons, it's not that much more to just get the cabana. RP has a very nice beach. We always go here when we cruise to GC. If you are going at a peak time, a cabana is good to not be in the crowded section--we were there Easter week with 5 ships in port.
We have always just walked out from the port and taken one of the many minibuses going straight to RP with cruise passegers for $3-4PP each way. They are many waiting for returning to the ship as well. The minibuses might have seatbelts--it's a short drive and they don't go very fast--not that an accident couldn't happen. I bought a travel vest portable car seat thing when my kids were younger (but then never used it). $200 is VERY high for a transfer to RP--I have walked it before on a fitness walk. It's not even 5 miles, I bet. I would be much more concerned in Cozumel with car safety.