A really great loan officer will explain to you that the length of time you lock an interest rate for is going to effect that interest rate. The longer the rate lock, the higher the rate.
With the current market and interest rate, it is not really necessary for you to consider locking until you are ready to get your loan documents to the title company. Rates have been low and the fluctuation in the market up and down has been so slight, that a rate lock would just be wasting your money.
As far as shopping for a loan. Yes, you can call, but WHO are you going to call? Here is where it gets tricky. When you are shopping for rates, you should seek referrals from your friends, coworkers and, if you are a buyer, your real estate agent.
How do you shop for the rate? Bottom line? We all have the same money from which to pull. If yo ask the proper questions, you should be able to make your selection, not so much on the rate, but the rapport that you have with the loan agent.
Let the loan officer know your credit score. Let them know the approximate value of your home. Both the credit score and the equity position of your home will effect your interest rate. You should be given an interest rate quote that includes the APR (annual percentage rate)
The APR will be slightly higher than the quoted interest rate. The APR takes into consideration all the closing costs you will be paying for this interest rate. **** The larger the gap between the APR and the quoted interest rate, the more you are paying for the loan.****
In the end, you will find that you are making your choice not wholly on the interest rate, but on who gave you the most information without making you feel 'sold'.
In regard to credit reports, you have 30 days to have lenders run your credit report without your credit score being effected. After that 30th, any credit run by a lender/mortgage entity will effect your credit score.
Credit reports are good for 90 days. After the 91st day, your credit can be, once again, run by lender without it effecting your credit.
Keep in mind a lender should not be running your credit without your written consent.
If you want to run your quotes by me: email@example.com. I can give you feedback on whether or not they sound competitive.
Bottom line: just keep asking questions!! :)