Using somebodys else Residential Lease Form

[Pavlos Kasselouris]

I recently bought a property with an established tenant. The lease which I assumed was drafted by an attorney (about 10 pages long). Till now I used the Florida Realtors "Residential lease for Single family Home or duplexes" (about 19 pages long)

I actually liked the way the attorney drafted the lease, because it felt a lot more simple for tenants to understand, and it focused exactly in issues that mostly occur. The Florida Realtors one, I know that it is compliant 110% on Florida Landlord-tenant law, and covers every detail.

My questions are a) can I use the new one without the attorneys permission if I change it a bit? 

b) Which one would you use?