When Amazon has a pre-order price, does it stay the same price once the item is released? Does it go up either at release or the week after? Basically, I was hoping to wait until the release of a couple titles to see if any other stores would have better prices, but I was afraid prices at Amazon might go up if I didn't order now.

Amazon quite often raises the price after a title is released. What I like to do is to preorder at Amazon to lock in the price. Then I check this forum the week before the title is going to be released to find out what the other stores are goinig to charge. If the price is cheaper than Amazon, then I just go to Amazon's site and cancel my preorder. You can cancel a preorder as long as it hasn't entered the shipping soon stage(this usually occurs the weekend before release).
BTW, this probably should be moved to the Store Forum.

Often, if the price goes down after you preorder it, Amazon will credit you the difference. That's what they did when I preordered Harry Potter book 6 in January for $16.99 and they gave me a $1 credit back to my card because it had gone down to $15.99 at release time. They have also done that with some DvDs I preordered.