My lease states that if someone additional lives in the property for more than 48 hrs, the tenant must get written permission from the landlord. 

With your permission, I’d like to use that again.

I've also had prior landlords wanting to establish my identity and the tenant's permission prior to releasing the information - which is perfectly valid and was satisfied by faxing over the applicant's signed release.

I imagine that most of those tenants would have lease language specifically prohibiting such happening without permission of the landlord, or face some higher fees or default under the lease.

He did this without my written permission, which according to legal zoom he can't do.

As @Steve Babiak & @Kevin Perk stated tax sales often have a cloud or title defect, since a third party (the taxing authority) sold the property without the owners permission.

If any repair is going to cost more than x dollars they should need your written permission in advance.

I really liked them both and they came back the next day with the application (my permission to investigate).  

You'd need to get the Bank's permission is the short answer.  

It was my understanding that Appfolio has a feature that others don’t ,  and that feature is collecting the money automatically from the tenant and the tenant cannot change the date of collection without the landlords permission, is that right?