What time of year is best? - I like late April (after the 3rd full week of the month) or early May. That way, it's warm enough to go to the water parks, but not so hot that it's unbearable and you have to take a break to keep up your energy. Also, you'll miss all the school vacations.
What hotel to stay at? - I like the Wilderness Lodge (don't really know why...I think I just like the laid back feeling you get as well as the feeling of being camping while not actually having to be outside). Of course, if you want to have quick access to the MK, go with Contemporary, Bay Lake, Polynesian, or Grand Floridian. If you want to be close to everything, Coronado Springs is the place to be. It's also a moderate resort, so it'll cost you less, but if you book there, make sure to request to be as close as possible to the main building. Otherwise, it's quite the walk to get food or anything else you may need at the main building.
What restaurants? - Magic Kingdom: Liberty Tree Tavern of the Crystal Palace (although the CP is not as good, but is fun for character dining) EPCOT: too many to name, but my favs are La Cellier (which is now signature dining for dinner) and Rose and Crown. They're pretty much all good, however, I was not a huge fan of Akershus. Hollywood Studios: 50's Prime Time Cafe has good food, but I don't like how the Cast Members are so into character that they can sometimes be jerks (in case you're not familiar, they act like your parents, or at least parents from the 50s, so they constantly "scold" you for having your elbows on the table [even if it's just your forearms] and they are very forceful about making you eat all your food, even to the point of being degrading). The last part is the one that bothers me the most because they'll do it even if you tell them that you're full. I can undestand this being part of the character because kids will lie about being full in order to get out of eating vegetables, but when an adult tells you they're full, you might wanna break character and just drop the issue. Anyway, I digress...the Sci-Fi Dine-In theater is a fun place to eat too. Animal Kingdom: I was not a huge fan of any of their restaurants, although a lot of people like the Tusker House. I personally didn't see what was so great about it.
Any special activities?? - Any of the tours are pretty fun. Magic Kingdom: Disney's Keys to the Kingdom Tour is good. Make sure to do Wishes at least once. EPCOT - Around the world at EPCOT is great, although the tour guide largely makes the tour (be forewarned though, it's on Segways which take a bit of time to learn how to use...but they give you that tutorial at first anyway).
Special activity/dinner - The Hoop De Doo Revue is awesome, and I remembered liking the Spirit of Aloha show at the Polynesian when I was younger, but when I saw it a couple of years ago, I was not impressed.
One last thing about converting you BF to a Disney lover...I hadn't been in 13 years when I went in 2009. I was expecting to have fun, but after being there for about 30 minutes, I became a total Disneyphile. Now, I can't get enough of Disney. I starting buying all their Blu-rays, I've read up on the history of all things Disney, I try and catch everything I can about Disney on TV and when I'm not at Disney World, I miss it everyday. I'm sure your boyfriend will love every minute of it.
Oh, one more last thing...I agree with Frau. You don't want to schedule everything. It's no fun that way. One thing you do want to schedule, though, is how much time you spend at the different parks. For instance, EPCOT is so big that you can't do it all in one day and enjoy it. I'd suggest doing Future World one day and then going back and doing the World Showcase another day. If you can take a 7-day or more trip, that'll leave you plenty of time to see and do it all while still enjoying it all.