Ah! Lots of questions - let me see if I can address each of them.
1. If your s/o dies with a will, naming you and/or your granddaughter as the beneficiaries of the property under his estate, then the property would pass to you and/or your granddaughter, however, it would need to go through the probate court.
2. If you marry now, you would be entitled to a half interest in the property as his wife.
3. If he quitclaims the property to himself and you as joint tenants, you would inherit the property when he dies, would not need to be married (although you could marry) and it would not have to be probated.
4. Unfortunately, I do not know Michigan law. Hopefully, an attorney from Michigan can post an answer regarding the foreclosure (you might want to try posting that portion of the question again, in the hopes that someone will answer). In Cook County, (and in California) the court will not allow pursuit of a claim of the deficiency after a foreclosure for a first mortgage, so if it were foreclosed here they could not take your Illinois home. I just don't know about Michigan. You might consider a short sale of that property and get a release from the lender of the balance. I might be able to help you with that, if you would like to contact me.
This answer does not constitute legal advice and does not and is not intended to create an attorney-client relationship. The law may vary depending on the state in which you reside. It is intended only to give some direction in which to seek assistance.