Most mortgage lenders use a specific version of the FICO score that may be different than the ones consumers obtain through other sources. However that’s less a function of the fact that a reseller is involved (which is common in the mortgage industry which needs tri-merge reports) and more due to the version of the FICO score that meets Freddie/Fannie guidelines. We wrote about different credit scores in this article: Why Do I Have So Many Credit Scores?
Checking your own credit score will not impact it in anyway positively or negatively. There is a difference between doing a soft credit check, which is what utility companies, landlords, or cell phone companies may do to see if you qualify for perks such as not having to pay a downpayment, and other types of credit checks that lenders usually do, which are called hard credit inquiries. Hard credit inquiries will typically reduce your score by a slight amount, but only temporarily until you start paying your loan.
Annualcreditreport.com and the nationwide credit reporting companies will not send you an email asking for your personal information. If you get an email, see a pop-up ad, or get a phone call from someone claiming to be from annualcreditreport.com or any of the three nationwide credit reporting companies, do not reply or click on any link in the message. It’s probably a scam. Forward any such email to the FTC at firstname.lastname@example.org.