Based on the will, an initial court filing will propose this person as the PR or executor subject to a future court hearing.

If you specifically say "safety reasons," it's going to look pretty lame to accuse you when something unsafe happens.If they do it anyway without your knowledge, at least you have something pretty good for court.

I’m wondering if I would have personal liability in court if the mortgage is under my name, or if I would just be seen as an equity investor in the LLC, and the only thing at risk would be the property that the LLC owns. 

(Unless MA includes some listing through non-judicial process) Your first opportunity to see foreclosure actions will be publication, notice of foreclosure and those should also be filed with a county clerk's office or clerk of court or similar administrative side as the process is non-judicial, the court isn't involved so it's not a matter before any court.

What's the most efficient way to find the property address as they are listed by a partial court case number withe the bank name and owner name?

My other concern for rent to own is contract or not, if the tenant can't get a loan in 12 months and you keep the $10k do you worry about ending up in court?

I read the creditors and IRS take priority over tax deed holders in case where the original owner of the listed property declare bankruptcy. 1 - Which department in the county should I go to clarify all this information and previous searches? 

I'm not trying to discourage you, but Southern California probate mailings from the court probate filing is a very over saturated list. 

Such matters are filed in the Circuit Court and you need a title binder as you have to notify all interested parties. 

The courts will generally throw out any sort of pre-signed deed in lieu of foreclosure (i.e. a "deed-in-lieu" or DIL) if contested by the borrower.