Mortgage question regarding commercial property....

[daytona]

I was wondering I got a commercial property for sale...no mortgage .....I got a buyer for the property and hes going to put %25 down and I would provide the mortgage since its almost impossible for hiim to go the normal financing route since his future income be tied into buying this property and operating it.What kind of precautions should I take just in case he defaults.Should I carry any sort of insurance?.....how many payments can he legally be late before I take action against him?.....