If your tenant did move out early, do not let him leave without signing a statement that he has moved out, that he gives up all rights to the property and anything left behind, and that he acknowledges any amounts owed.

While @Wes Brand's warning should be acknowledged, our experience has been if you screen well and provide your student tenants with well maintained, quality accommodations your properties will be treated with respect.  

Lots of investors came in because of people like BiggerPockets and other souces acknowledgement of it being number one in in investing return.

You acknowledge you'll have vacancies.

The things I read tend to acknowledge the upside but not the down side of investing.

As long as inspection period went and you got their requests or their acknowledgment everything is good you should be set.In all honesty if you never got the addendum signed when all contracts were initially signed you are to blame.

(Acknowledging that is a blanket question)2.

You should put rental criteria in the ad you place, or type up a list of criteria and have applicants acknowledge it when submitting their application. 

If you can't get that, have each of them drop the keys in the mail box and acknowledge it with a text or email.

"Buyer and seller acknowledge and agree that, because the purchase of home is one of the most significant investments a person will make in a lifetime, all aspects of this transaction require considerable analysis and investigation by Buyer before closing title to the Property.