I'll try to go in order:
*Embarkation was chaotic and confusing. We got put in the wrong line and had to switch after waiting through it. Had to show different papers to different people at different "checkpoints" and it wasn't clear what the logic was behind each of the requirements at each place. There wasn't much information about what to do when you first got on board (for example, I didn't realize that our SeaPass cards would be in an envelope on the room door...) Also, our TA had put in the request for our room to have beds together and kids to have beds apart - both sets of beds were together and we had to ask our room steward to separate them. We had to wait for a bit for the room steward to get approval to unlock the connecting door and we were trying to unpack our shared suitcases by going back and forth through the main cabin door so the kids got locked out at one point and we had to wait for them to be let back in. I wish there was a way to ask for all of these "connecting room" issues ahead of time. We also had to wait for someone to take down the separator on the balconies.
*I had seen it recommended that you get onto the free Royal Wi-Fi in the terminal in order to make reservations but the shows were all different than I expected and it was too hard/confusing for us to do it there. I had to wait until we sat down at Windjammer and could look at all the show times, which was a bit nerve-wracking because we didn't board until 1pm and I thought the shows might be fully booked. However, I don't know if any of the shows during the whole sailing fully booked up so that ended up not being a problem. I was even able to switch our Mamma Mia reservation on the last day from the afternoon show to the evening show with no problem, that morning.
Cabin was awesome. Bigger than I thought it would be, having only cruised RC interior cabins on Freedom class before this trip. Loved the couch by the closet/bathroom. It was awesome to have a balcony (but would have preferred loungers rather than stiff chairs). Bed was comfortable. There was enough storage for our clothes and items, although not quite enough in the bathroom. I would have loved to have one slightly wider shelf available.
We did two different things on Cozumel. We booked at Cabana Beach for the snorkeling and access to Chankanaab but also wanted to go to Paradise Beach with the kids so they would have a chance to do the fun climbing inflatables for a while. We got in the cab and the driver started going but told us that Paradise Beach was full and we should go to this other place for only $20/person. I doubted this because they usually post on their website if they were full AND they didn't tell us at the port before we got in the cab. Our phone plan works in Mexico, so we immediately tried to get on to call but couldn't get the connection and phone number in time so we just had him drop us off at the Cabana early. Once at the Cabana, we were able to connect to Paradise Beach, which was NOT full. The cab driver lied to us to try to get us to go to this other place - so beware. My husband had to be on a work call all day, so he decided to stay at the cabana to work and I took the kids for the morning over to Paradise Beach. They had a BLAST on the toys and we had lunch there which was delicious, and we headed back to the Cabana. We got our snorkeling gear and went in the steps - the snorkeling was amazing with many, many fish. The water was cold at first but wasn't bad once you were in. The equipment wasn't great and kept fogging but it was worth it to just keep trying. There were a ton of different types of fish right along the rocky shoreline. The staff was great. We got some fruit and some drinks and my husband got lunch, but when we went to pay, their credit card machine was broken so we had to use extra cash there and for a 4th cab that we weren't expecting that day. We also walked around Chankanaab but it was really, really hot at that point and there wasn't much to do in the park that we couldn't do at the cabana. I wouldn't buy the park tickets if I went back again, although it looked like a nice alternative place to spend the day if you didn't book the cabana.
This is a strange port. I guess the actual port is nice with the swimming pool but it is really far and confusing to reach the taxis if you want to go anywhere else. The taxis seemed expensive to go such a short way ($4pp). We spent the day at Jaime's at the Blue Reef. Food was great, drinks were good, the shaded chairs were nice, and the staff was very friendly. The service was a little slow and the bathrooms were quite shabby. The pool on the roof was really cool and views were amazing but it was a hike up all of the stairs. My 12 year old really enjoyed the stand up paddle boards. My husband and I took a snorkel trip out (extra fee) where we saw a bunch of fish and a big eagle ray. We did not use the kayaks but they were available. We were there with friends and were talking - otherwise we might have gotten bored. There were also many, many vendors coming by with items for sale.
You can tell that this is a very poor country, especially right in the main town, but this stop was one of the highlights of the whole trip. It was a strange place to meet our non-Royal excursion tour (through Viator) - on the side of a road, in a crowded, sunny space, and then back into a impoverished neighborhood to get into the van. One we got going, we could see the beauty of the island. Many hills and very green - our driver gave us some info about the island as we drove. We did a Sloth/Snorkel combo tour. AJ's Sanctuary for the sloths (also guinea pigs, birds and capuchin monkeys). That was amazing - especially the monkeys who were hilarious. Then we did snorkeling in extremely clear, warm, shallow water and saw many fish, spiny lobster, conch in their shells, and a giant crab. We absolutely loved this experience.