To me, seems like a lot of to do over nothing. Why didn't you just wait and order after your trip? Or have someone retrieve the package for you? I can't think of a single time that I gave a vendor instructions like that. I would have very low expectations if I did, most places aren't good at...
I clean the grates/grills, and occasionally will hit the back and sides when I am brushing the grates. I'm not looking to remove the "seasoning" on the sides and back, just knock off any loose particles. I change the foil on the drip tray pretty regularly, but IMO no reason to "clean" it...
Just sealed my Bull, big difference, and my temps are staying spot on.
One thing I noticed is that the bottom edge still lets a little smoke out, looks like some small weights on the horns would help, but I don't think it is worth the effort.