Many questions: What kind of legal agreement would you recommend to lay all this out and ensure a fair and transparent agreement?

We are living in the main front house and renting out the ADU to a tenant.My question is, other than having landlord insurance on the ADU, a solid lease agreement, and a 3rd party management company as intermediary to help manage repair needs/requests (my partner and I both work full time jobs) and showings when the unit is vacant, is there any legal entity protection or other avenue that will protect us further in case of a tenant lawsuit? 

When asking the owner about the tenant her story is that he moved in under the agreement to fix up the property and had done the opposite since, all without paying any rent.

Maybe they come to an agreement, maybe not.

The underwriter just needed to know that the lease agreements would either expire or were month to month, and that one of the tenants were informed about the purchase. 

Do you have a lawyer to look over the  purchase agreement? 

The previous owner had some lease agreements in place, but they were 35+ pages long and a little out of date.

Get an agreement in writing so that they don't try and jack up the price after a couple months.

Can anyone recommend a Florida lease agreement geared toward an owner occupied property or would a standard contract suffice? 

How or where can I find that type of contract agreement?