It’s never been that busy that we had to worry about our items. It’s a nice small place, everyone looks out for each other

You could pre-book your golf cart but then you have to find them which can be hard. I personally would just exit the ferry and look around the golf cart companies are everywhere. If you walk in a few blocks the prices are a tiny bit cheaper. I would get on the island early cause the daily golf cart rentals are 9-5. I am assuming you are just going to the day. If not do the 24 hour rental they will drop off and pick up at your place. Also don’t pay all the money to go to the garrafon state park do garrafon de castelle. It’s a lot cheaper unless you want to zip line. Look up the difference they are next to each other and a huge price difference.

I'm pretty sure is was around 100 pesos for the day

from the ferry terminal to Garrafon de Castilla should only cost 100 pesos per taxi and you always need to confirm the price with the driver before getting in. We just got back from spending two weeks on Isla Mujeres and had nothing but great experiences with everyone we met (restaurant staff, taxi drivers, ferry terminal employees)

Pienso que si.

Definitely not on the alcohol. There's no need to rent chairs, since your entry fee includes them.

We always get there a few minutes after 10. Make sure you go to Garrafon de Castilla and not Parque Garrafon. The latter is the one with the zip lines.

There is a lot right by the entry where you pay. At the bottom of the hill off the main road.

Was there in November 2018 and outside food and drinks were not allowed.

Yes, used mask, mouth piece and flippers (the flippers for an extra charge, but I don't think it was too much). Next time though, we'll probably take our own - at least the mouth piece.