I know this is an old post but I wanted to comment for those who have the same questions that may be viewing these answers. I work mostly in Fairfax & Loudoun Counties in Northern Virginia. Rules may be different depending on where you are so please always contact a mortgage broker to ask specific questions...
When looking for a home generally you have 30 days to where your credit will not be hurt multiple times while you are shopping for 'mortgage rates/lenders'. You will only get the 1 initial inquiry as your credit is being run.
Lender #1 Pulls Credit ---Start of 30 day clock. Initial Inquiry (as they are the first to check the credit)
Lender #2 Pulls Credit w/in that 30 day period ---No reduction of score
Lender #3 Pulls Credit w/in that 30 day period ---No reduction of score
Lender #4 Pulls Credit w/in that 30 day period ---No reduction of score
Now of course rules change all the time so always check with your lender, or even call any of the 3 large credit reporting agencies (TransUnion, Equifax & Experion).
There is also a new tool that is 'actually' free you can check your credit...CreditKarma.com. They dont ask for any credit card info like other sites.
Should anyone need help or anything else, you can always conact me and I will get you the answers you need.