I recently had a friend call me upset about some work they had done by a photographer. I shouldn't say work, because they loved the photos that were done. She was upset because of what she got back, or rather, what she didn't get back as part of her package.
Any photographer that you hire is going to have a thorough contract that comes with hiring them. Just as a side note, I'd actually be concerned if you don't receive a contract of some sort from a photographer. Contracts not only protect the photographer, but they also protect what you're investing in. Verbal agreements mean very little at the end of the day.
I try to always make it a habit to give clients an opportunity to go over their contracts or at least make sure they read through it. You never want to get into that conversation with a client where you state something is in the contract and they have no idea what you're talking about. More than that, I want them to ask me questions about the contract.
I'll admit to being guilty of 'skimming' through contracts without actually having a clue to what is in it. There can be a lot of confusing talk in contracts, or terms that you don't even think apply to you. There's quite a few lines in my own contract that clients question, "The photographer(s) shall not be held liable for any and all injury to the client(s) during the course of the session and the immediate surrounding events." Seems like an odd term to have in a photography contract, or at least I get asked about it often.
Do yourself and your photographer a favor, read through your contract, ask lots of questions. Know exactly what you are getting with your session, ask specific questions about that as well. How many pictures are you getting? What are the costs for additional images? Do you get your images on a cd/zip drive? Are there restrictions on printing? What are the costs for enlargements through the photographer? Do you get a print release? These are just some of the many questions you should be asking your photographer.
Most photographers are going to be upfront in their contracts about what you are getting. Most are going to assume that you read through your contract as well.