Unfortunately there is no easy answer. Some houses sell for well below asking price, while other sellers receive multiple offers and end up selling for more than the listing price. It all depends on how well the house is priced in relation to current market activity.
You can either use Zillow's e-mail alert system, or sign up for a free account through a real estate agent that will give you access to MLS information.
It all depends on your personal situation. Interest rates are low and prices are lower than they have been the past few years, but your wants and needs will determine if it is the right decision for you. It is also harder to get financing now than it was a few years ago. If you are thinking of moving again in the next couple of years and selling what you buy now, it may not be the best decision, since prices aren't climbing very quickly (if at all) and a commission will be deducted from the sale proceeds. On the other hand, if you are planning to settle in somewhere for a while and find a house that works great for you, it could be a great time to buy.
If it is a new or relatively new house, you may be able to get the information from the real estate agent involved in the original transaction. Otherwise, you should be able to find out who the builder was by doing some research at the building department.
Following up on Jim's comments, properties that are listed as Pending are often still shown to prospective buyers, and back up offers are taken in case the sale does not go through due to an unsatisfactory inspection report, inability to get financing, or other conditions that can't be met.
A builder's organizational skills are important for getting your project done on time and on budget, and those skills may be represented in how prepared they are for your interview. If you are going to be significantly involved in the process, make sure they are a good personality fit for you, because you will be dealing with them almost every day for several months. Many builders work on multiple projects at one time, which is efficient and cost effective for them, but may mean your house will be at a stand still while they are working on something else. Make sure you have an understanding about this before you begin. Also make sure they are licensed by the state, and check to see if any complaints have been filed against them with the state agency that oversees them. Ask for references - both current and past, and ask if you can see work completed or in progress.
Zillow allows agents to register on the site and post their profiles, but does not employ them. Ask friends and neighbors for agent recommendations, and work with one who you find knowledgeable and think will be a good personality fit for you.
I've seen houses that are listed in the MLS as either for lease or for sale show up in Zillow as a for sale, but with the lease price. Your best bet is to call the listing agent to clarify.
Ask friends for recommendations - if someone you trust had a good experience with an agent in your area, you could talk with them and see if their personality is a good fit with yours. The home buying process can be stressful, so make sure you feel comfortable with your agent and their ability to communicate with you.
Contact the school district to confirm which school your children would go to if you bought a particular house, and to make sure that the school has space available for new students.