Hi in too deep:
First of all, you'll love The Blue Angel and all of the staff. They make you feel like part of the family. As far as water temp, I think there's a "sticky" on the forum that can give you the temp info. I've not been there in January, so I don't want to speculate. Where to eat: the restaurant at the BA is great! You don't have to go far to get good food. And if you don't see what you want on the menu, just ask...they'll usually be able to fix what you want. I like oatmeal in the morning and it's not on the menu. I ask...they serve a great bowl of oatmeal! There are many good restaurants in town. On this forum, Christi has a list of favorite restaurants. Take a look at it. A couple places we really like are Ronaldi's (about 15 minute walk from BA) and O'Hana's (about 30 minute walk from BA). O'Hana's is owned by BA instructor Mateo and his wife. The food is excellent! Don't miss out on eating there at least one time during your stay. You can get fresh fruit at Mega and Cheruai (sp?) which are huge stores about a 15 minute walk from the BA. The BA has a very nice open-air lobby for hanging out; people hang out in the restaurant...especially in the evening when they have live entertainment by a gentleman who plays the guitar....muy bueno!!; and each room has its own balcony (ground floor rooms have more like a patio). People also hang out around the pool in the lounge chairs. Don't know about a gym....I get enough exercise schlepping my gear up and down three flights of steps every day as well as walking into town daily....about a 30 minute walk. To get to the resort you need to buy a ticket at the airport. Once you clear Customs, walk out the door and you'll see a counter where you purchase a ticket to get on a van to take you to the BA. Ignore the timeshare hawkers and plow through to the counter. Once a van is full, off you go to the BA. We always take a taxi back to the airport for our departure.
You'll have a wonderful time at The Blue Angel. You biggest concern will be----how soon can I come back!
Happy diving!