Number of Photos
One question to ask your photographer is how many pictures they typically take at a wedding & reception. For me the best answer is always "there's no limit, but on average I take about _____ photos". Unlimited photos are definitely the way to go. I like to hear at least 400 for the average number of photos. 400 is plenty as a minimum for most weddings, unless you're having an unusually elaborate affair or multiple ceremonies. Do NOT go with a photographer that says they will stop after a certain number of photos, unless that number is absurdly high.
For example, 200 photos could be enough, especially if they are all fabulous, but in my opinion it's better to have more. (It's very unlikely that every photo will be fabulous.) It also depends on how long your photographer will be there for and what you want photos of. The least I've ever shot was about 400, and that was at a wedding that I was only at for 2 hours. My average is probably 450-600 or so, but I've taken as many as 800. When you get past 500 or so you start getting a lot of duplicates (which is helpful for group photos, because there's a better chance of everyone smiling at the same time in them) but not so necessary of the two of you walking down the aisle. (3-4 will usually do it, 10 is overkill but if doesn't hurt anything if you're doing digital.)
So keep in mind that it's not so much the number of photos that matters, it's whether they get all the shots you want or not.