I offered to lease the property month to month at a rate 25% higher than a 12 month lease, and have his security deposit forfeited if he left prior to 3 months, and 50% forfeited if he left month 4-6.

Keep the title the same, keep the original entity alive.Some attorneys and gurus tell investors LLC vesting is the secure manna from heaven but fail to detail the long term costs and pitfalls.

They want to terminate the lease (month-to-month lease) and use security deposit as last month of the rent.Problem is there's no security deposit in the lease when I got this property from previous owner.

Their company has paid the security deposit, so if she were moving out, I would use that money to pay for the costs but there is still 4 months left on their lease (and they have already said that they would like to sign again at the end of the term).

If you've been in the Miami housing market hunt for any length of time, as it seems you have, you'll know then that even with good employment, good credit, and a sizable down payment it's STILL difficult to secure a house.

I am so excited for what is to come with my decision to pursue real estate as a way to secure my families future. 

As such, I reimbursed the security deposit to them written to "The Estate of Tenant's Name".

What’s a creative way to secure this house to either flip or wholesale out?

Do appraisers automatically include a 10% property management fee despite it being managed by owner or if its possible to secure a lower say 7% management fee?

You can't generally solicit securities offerings without an exception from the SEC.