We are going to Playa del Carmen for 5 days in December. There will be 4 of us and we will be staying at the Shangri La Caribe
1. How to get to PDC from the Cancun airport - should we rent a car or use a van service to get to PDC? Any suggestions for car rentals or drivers/vans? Is it an option to rent a car at PDC for a few days? More or less expensive?
2. Water - is the water purified? Can we have those wonderful frozen drinks at Shangri La Caribe and in town or should we stick to cervasa?
3. From hotel to town - is it a walk or a cab ride? How is parking in town?
Thanks in advance for any advise!

Well I'll throw out some answers, for what they're worth.

1. Impossible to say about the price difference, as there are numerous options for either transfers or car rentals, but I would recommend the transfer, since you have a relatively short stay and since it's very easy to get around in Playa without a car. This would go double if you're new to the region, since you'll have all the more to discover on foot.

2. The water you are served everywhere is fine. Same with the ice. Remember that if you "stick to" cerveza or other alcoholic drinks, as you say, you will become more dehydrated, leaving you more vulnerable to illness from any angle.

3. Shangri-la is a bit north of town so you may not find walking to town (as opposed to walking around in town) to be so easy. BUt it would be a very short cab ride. And parking depends on the season, but again if you do transfers and then take a very quick cab ride into town, that won't be an issue anytime.

Steve

Possibly the cheapest and easiest way from the airport to PDC is the Riviera bus, which leaves the airport roughly every hour. The fare is about $7, and it only makes one stop en rout to Playa, so the trip takes about 45 minutes. Since locals as well as tourists take the bus, it's a good way to immerse yourself in the culture. The only drawback is that the bus pulls in right in the heart of the city, you'll need a cab to get you to your hotel.
As for the water - many places stste on tehir menus that they use purified water, and the produce is washed in a mild antiseptic. I personally would stick to bottled water and beer!

We stayed at Shangri La Caribe this summer for a week and had a wonderful time. Here are my answers:
1. We had a van arranged for by Shangri La pick us up at the airport and did not rent (or need) a car while staying at PDC. If you would like to rent a car in PDC for a day or two, there are plenty of agencies in town and the prices seemed reasonable to me. When you are renting at the airport the price is usually higher due to additional airport taxes.
2. We had absolutely no problem with the water or food at Shangri La. We had frozen drinks and water poured from jugs at dinner and none of us had the slightest problems. The hotel provides bottled water for the rooms as well.
3. It is an easy walk to the center of town (either along the beach or along Quinta Avenida). If you are coming back to the hotel at night or have done a lot of shopping ;-), you should take a taxi back to the hotel (easy to find and inexpensive). We haven't tried parking in town, but I would imagine it is not easy as the area is densly built.

Last time in Playa we went with 2 friends and took a van from the airport. It came to about $15 a head and we were taken right to our hotel, no stops along the way. Just beware of the time-share vultures as you leave the airport -- walk right by them and do not make eye contact!
We like to stay at the Pelicano Inn (at 8th and the beach), but walk up the beach past Shangri La to snorkel. It's an easy walk and, if you get thirsty along the way, there are plenty of beachfront restaurants to stop at and have a frozen margarita! All of the ice is made with safe water -- making the tourists sick does not help sales. The only problem we've encountered is an occasional lack of electricity, but margs on the rocks are just as good as frozen, as long as your toes are in the sand!

I went there last Thanksgiving, and just had my hotel arrange for a private van pickup and return. I liked that option a lot. I am surprised your hotel hasn't offered that possibility, as I think it's as high level as the one I stayed at (3* Mosquito Blue). I think it cost about US$45 one way.

I drank the local water with no problems. I read that PDC is one of the places in Mexico with decent water, as well as Puerto Vallarta (probably some other large tourist areas), so I wouldn't worry about it.

I didn't rent a car so don't know the price comparison for that. I wouldn't bother if you just intend to stay around there.

It's funny but when I was meeting my van driver at the Cancun airport, I never noticed any time share vultures at all, and none of them talked to me. I don't pay attention to people like that though and won't even talk to them because I just have no interest, so maybe they can tell that.