Insurance can be an issue as you would technically have to get it in the LLC's name and then you can have a personal umbrella to cover any overages. 

Quote from @Nick Grassi:Not sure about Florida, but my experience with solar.. 5 years or more ago, buyers would take over leased panels and not have any issues with getting a solar lease from the owner prior to them.

I have heard that leaving 1/4 " along the perimeter can help expansion issues. 

The ground is now about 4-5 inches below the foundation line and it's also causing issues with my neighbor's adjacent yard.

. $3k to fix the issue sounds like ROBBERY!

The heavy cleaning and repair costs after longer stays are definitely pain points but I've seen my clients make it work by screening the tenants more carefully for MTRs, doing bi-monthly checks to catch issues early, and writing clear lease terms about maintaining the property.

Please do not act as an unlicensed manager, it will only result in issues for both you and your friend.

Learn issues buying tax properties.4.  

If mold remediation is done by a handyman without air sampling or post-remediation testing, it can lead to issues during the sale.

Rent controls will be a real issue if you are planning it as a rental investment which in fact reduce the value of the main house as a rental.