With that said, I noticed that CAPs in Florida are around 5 to 6%.

People are not simply going to trust you just because you have a sign on your car, or a T-shirt that says "No really, I won't  scam you no please please please believe me I am begging you".That sign or T, just gets you noticed.

I did not notice until the husband demanded his security.

Set the rent and put in the lease that you will give a 30 day notice for vacating his things.  

Raising Rents on Long Term Tenants requires 60 day notice with section 8 (while not losing a good long term tenant).

A foreclosure notice that was mailed first class to the previous owner in November 2019.

To soften the blow, you could even print a recent article that explains why rents across the country (or your particular area) are increasing at such a high rate.This gives you 3rd party verification and shows you are not just pulling numbers out of thin air.I imagine the tenants will not be surprised, and will likely be wondering what took so long for the rents to increase over the years.I read a recent news article about a lady in Plano, TX that got an increase notice of $750…yes $750 on top of existing rent rate. 

If he does not pay his share of rent and doesn’t show up or contact me before the last day rent is due, can I send certified mail to the address and email him a notice that the lease is being terminated due to his nonpayment of rent?

I've noticed reverse searching the MLS has worked for me.

I have a pre-approval notice, and I'm not sure what the legalities of sending it out to agents or exposing it are.