Also, regardless of what happens, if you get a summons to appear in court, make sure you go. If you don't go, the landlord could lie and get an eviction anyway, which you would then have to fight from a weak position. If the court asks for an answer to the complaint, send a copy of your docs and a concise description of what happened.
I agree with this statement. 99% of the time my tenants don't show. When they do show they usually don't have a case anyway.

Also, it sounds to me like you need to pay every single payment by certified mail. You need some sort of tracking through USPS, UPS, Fedex, etc. This sounds like it will be an ongoing problem.