Let's answer question 2 first. Yes, since this is not the first year that you are treating your wife as a resident, you can file separately, then go back to filing jointly the following year.
As for question 1, if you file jointly you would have to include the sale of the house on your U.S. tax return. If you file separately, you would not have to include the sale of the house on your separate U.S. tax return. But since your wife has chosen to be treated as a U.S. resident, she is required to file a U.S. tax return and she would have to include the sale of the house on her tax return. If she sells the house "soon after" she inherits it, she would not qualify for the exclusion of gain on her U.S. tax return because she would not have owned the house for 2 years before selling it.
You could possibly revoke the choice to treat your wife as a resident, but revocation is permanent. Once you revoke the choice you can never make the choice again.
Taking a quick glance at some of your previous questions, it appears that there are other considerations that you have not mentioned here that might make the situation more complicated. I suggest that you consult a tax professional who can review your entire tax situation and give you guidance.
Here are a couple of IRS publications that you might want to take a look at for some background.
Publication 519, U.S. Tax Guide for Aliens, particularly the section "Nonresident Spouse Treated as a Resident" in Chapter 1
Publication 523, Selling Your Home
