I have limited experience working around Mercury retrogrades (it wasn't in my consciousness until the last couple years), so maybe other, more experienced astrologers will have more to say, but here's my thought:
A job interview is not a contract, and the second interview might not be anything close to the final decision. Most people who pay attention to astrology don't sign contracts during Mercury retrograde, but that doesn't mean they don't consider anything they might end up signing a contract for. Mercury retrograde is a good time to make those considerations, in fact. It's a good time for thinking things over, looking into options, and doing the behind the scenes work.
During the last Mercury retrograde, it was decided, through discussion among a few people, that this forum needed at least one more moderator. I was asked if I would be one. Tim (wilsontc) didn't want to start me as a moderator during Mercury retrograde, so what we did was wait for Mercury to go direct, giving me a chance to think it over before jumping into it. I became a moderator when Mercury came out of retrograde.
If this had been a real world job search, it would've been the equivalent of interviewing during Mercury retrograde but not signing the contract until after. In the real world, most hiring processes move slowly, so it's not likely you'll have to sign a contract until after Mercury goes direct, even if you have the second interview early in a Mercury retrograde period. It's not even likely that you'll get an offer before Mercury goes direct, unless they're moving unusually fast with their hiring process.
Interviewing for a job isn't just about the company deciding if they want you, it's also about you deciding if you want them. If there are any fatal flaws with this company or this job, Mercury retrograde may be a very good time to discover them. It's certainly a reminder to do your due diligence before accepting any offer. It's a great time for thinking things over, which is what the interview process is for.
The process of finding a property to buy is similar. You'll probably look at several before you're even ready to make an offer. Mercury retrograde is a good reminder to check everything closely--hidden flaws may be easier to miss during that time, so attention to detail is especially important. If the property you're looking at has, say, termites or a bad case of dry rot, that's the kind of thing that Mercury retrograde might be good for exposing.
As for having your wife make the offer because she isn't a Gemini, that's flawed thinking. The people least affected by Mercury retrograde are not the non-Geminis, they're the people with natal Mercury retrograde. If your wife has Mercury retrograde in her natal chart, she won't be affected by Mercury retrograde, really. If her natal Mercury is direct, Mercury retrograde will have the same effect on her as on the majority of the population. Same goes for you.
What areas of your life are most affected by Mercury retrograde depends on which part of your chart Mercury is retrograding in and which of your natal houses are ruled by Mercury. If Mercury rules your fourth, sixth, or tenth house, or if it's retrograding in one of those houses, I would expect to see its strongest effect in your search for real estate (fourth) or your job search (tenth or sixth). If none of those houses are Mercury ruled or being transited by retrograde Mercury, it probably isn't going to have that strong an effect on that part of your life.
Your finances might be affected if Mercury rules or is transiting your second house (maybe your eighth, if you're looking to take out a loan and/or using inherited money for your real estate purchase). If that's the case, it's a good time to check your credit report, and make sure there's nothing in there that would get in the way of your purchase.
