More questions about taxis/prices and getting to and from san gervasio

[worry wart]

I saw on one thread on here a picture at one of the piers that had taxi prices listed for taking you to different places on the island. I was wondering if anyone knows if the prices are still the same. I wasn't sure when that had been originally posted. Also is it fairly easy to get off ship and hail a taxi for 4 or 8 people to take you to San Gervasio and wait for you there and bring you back either to downtown or drop you off at Playa Corona beach. Are there tour guides at the ruins that you can hire and do they work for tips or a price. If tips, how much is appropriate to give for a large group of people touring? Is it still 45.00 RT for 4? If you wanted to do an eastside excursion as well can that be done by a taxi driver or do you have to hire a tour service? Our ship Imagination gets in at 1:00 PM and I heard that San Gervasio closes at 4:00 but I guess with the time difference in Mexico we should have time to tour it? How long do they tours usually take there? Would we have time to snorkel for say 2 hrs. afterwards at Playa Corona or either take a tour to the east side to El Mirador or the lighthouse or would that be too much? We would like to get back to downtown before dark to spend a little time shopping. We don't have to be back on the ship though until 9:30. Anyone know what time it does get dark in Cozumel?? Also what time does the snack bar/snorkeling equipment area close up at Playa Corona or Dzu-Ha? Either place actually would be ok. Any help would be greatly appreciated!! We have a large group of people going but can break up into smaller groups for transportation if everyone decides on doing the same itenarary.