Also, tenant signatures must be gathered for Solar City to gain permission to access the roof since the tenants are technichally renting the property. 

Another neighbor's kid was playing on it with their kids, with permission, and she broke her arm. 

In addition to the above, if you give permission for them to run a preschool, where is your base line for "normal wear and tear"?

I'd tell them they were still responsible for the rent, and I'd give them written permission to have a long-term guest over the summer. 

Sometimes you can get out of that limit, if you have a very good reason your building can't handle that many people - old pipes, septic system, etc.As far as the BF goes, if she qualifies on her own, and would rather the BF not be on the lease, what I did was I'd put them down as having written permission to stay long-term. 

For he most part I will write a letter not allowing permission of use and contact of the company who took those photos for privacy because I personally don't want my personal space free to the public.I appreciate everyone's input.

Most people operate on the principle that its easier to ask for forgiveness than to ask for permission.

After that time is exhausted the tenant is required to obtain my permission to extend the stay. 

Under no circumstances would I tell one tenant any personal information regarding another tenant, without having explicit permission to do so.

I just gave them written permission to have a long-term guest.If you can contact the grad department and find out how to advertise to just the grad students, rather than advertise on Craigslist, etc., you can avoid having to rent to non-students.