I don't think calling to let them know you cannot get work off in that short of a notice would be a problem at all. I interviewed middle of may, and have a class date of June 18th. They asked me also if I could start two weeks after the interview date, which I said yes to, but my class date was 3 weeks after my interview date.

I replied to someones forum topic about a month ago with the kinds of things they asked me. Also, as he was saying above, most the mexican approach questions they ask you in the interview are about DME arcs. They had me finger fly a departure, asked about MCA's, airspeed restrictions, etc. Its all right there in the notes on the plate...just take your time and think about your answer before saying it.

If you have any questions, feel free to PM me.