I agree with the advice you're receiving here, however one thing I don't see pointed out is that you need to be careful in having too many loan officers pull your/his credit as this will negatively impact your credit score, which will impact your ability to buy...especially if his score is right on the cusp of qualifying.
I typically advise my Buyers to contact 2-3 loan officers, tell the same "story" and listen to what they have to say, as well as how you feel about the information and the connection, or lack thereof, with them.
Remember, this person will know all your intimate financial details, so you really want to get a good sense of trust, rapport, and friendliness. Sometimes this cannot be accomplished over the phone, so perhaps a meeting is necessary. Do not worry if it takes a week or two to do this, as houses aren't going up thousands each day, so take your time and be diligent about it.
You can Google questions to ask. There are also first-time Buyer classes you can take. Lastly, there are also Realtors who can help guide you as well.
RE/MAX Gold RE
Sr. Mortgage Banker
NMLS # 659743