For example, assume the old renters are paying $300/mo, and we expect to get $600/mo after rehab.Do we have to officially evict everyone? 

He even recommended I write up an official document that states what work was being done, that he would cover all expenses, and that he would leave the new toilet in place upon vacating the property at the end of his lease.Does anyone have experience with handling situations like this?

@Calus Glispie in my state you need earnest money to make an official contract.

One of the reasons North Idaho is so great is that our county officials are elected -- not appointed -- so they are more responsive to the citizens. 

This is my first official post...and a success I think.  

It became clear she wanted to milk the situation whether she had any legal standing or not.Day 3: Send written notice of change of ownership and officially serve 60 day notice to vacate.

I'm not super wealthy, but I do have some spoils of the trade to play with.I live in Malden, and have been educating myself to get into flips and rentals (loving BRRRR) in the area (Melrose, Medford, Malden, Everett, Saugus, Lynn, Stoneham, Reading, Woburn, etc.).I have never officially invested in real estate, but I have owned first and second homes for many moons, and they have been good to me so far.I've learned enough in my studies to know that real estate investment in this area and time is far from a no-brainer. 

I have submitted my first official offer.

I completely understand that investing can be accomplished without "official" education, I simply have a chance to further mine (so why not right?)

Letting him know the situation up front should deter him from returning to the property uninvited and forcing entry.I would think that contacting the guy would make it official that he knows that the guy is living there, which would put him at a legal disadvantage.