This home is now a vacation rental that can be rented as the whole home, sleeping 8, or more if you do air mattresses, or each floor is indpendantly rentable on its own.

I know it in my dreams, life and while i am sleeping i gets into property analysing and making transaction and investing.

Is email notification sufficient or do I need to post it on their door?

This should be sufficient to cover the expenses of the property (including vacancy and capex reserves!) 

The FHA Appraisal also has pretty specific sections including: No damage to the foundation, roof, or exterior, Safe access to the premises, Working utilities, No exposed wiring or other electrical systems, A permanent heating system that provides sufficient heat for the home, No peeling or chipping lead-based paint, Access to clean water, No termites or other wood-destroying insects, Access to, and ventilation in, attics and crawlspace, No soil contaminants, such as from a damaged underground storage container, No safety hazards, such as stairs without handrails, Compliance with local zoning regulations.

We're also wondering if we put in writing the following and they agreed via email if that's sufficient:#1 they are still financially responsible until we are able to rent the space#2 we're charging a turnover fee $1k to let them out of the lease early and collect that immediately#3 security deposit will be returned according the the RI tenant laws (ie place is left in same condition as move in)#4 room is made available at reasonable hours for showings/open houseOr do we need to hire an attorney to provide a lease addendum stating an early termination fee?

If you get into a 3 or 4 unit, you will have to perform what is called a "Self Sufficiency Test." 

This is mostly due to our homes comfortably sleeping 15-20 people and being able to target multigenerational groups who can split the rent.

Your basic insurance policy with $300,000 in liability coverage should be sufficient in 99.999% of all lawsuits.5.

Do you have sufficient capital reserve should the renovation cost more, take longer, or fail to lease up right away?