I offered $100,000 without knowing knowing the address or condition.

You can create a simple template on your computer and just fill in the blanks....for exampleName of tenants:  Address:  Amount owed. agreed payment terms:  Signature:  You can make this template as easy or as complex as you want.   

Get their name, address, email, cell, call them later.Hope that helps.

Ideally a site/software that pulls names and addresses from a database right into the letter text and on the envelope with a handwritten appearance.What's best and why?

It's hard to imagine, but I know there are architects out there doing some really intriguing things to address this lack of housing on micro scales or with unusual infill lots.Affordable is so relative too!

You might want to address child safety.

There were a few things that I am going to change going forward however, one thing that I wanted to implement was hiring someone who can visit the site weekly and report back to me if there are any problems or items that should be addressed. 

There's a couple of questions you didn't ask too and I'll address those too. 

You can only address normal wear and tear.

@Bryan Weiss I'm gonna message you to get the address and everything.