1: I doubt they would do both without seriously considering you for a position. But who knows with some companies.
2:I've dealt with a lot of HR people over the years and some are just horrible about doing there job.
3iffers with the companies I think.
4:If the MRO hasn't tried to contact you by now you're probably safe. BUT I have had a random 3 days after I was hired so do so at your own peril. I hiighly recommend synthetic urine to help stay out of trouble.