The "bank" (depending on where you cross) is actually just a different office in the same building. You'll also need to get some copies made after you get your permit, before you can get the TVIP. Agua Prieta is easy because you can get everything done right at the border crossing and everything is right there in one building - all within about ten feet of each other. I haven't done the paperwork anywhere else so I don't know what Nogales is like. You can get it done anytime, it doesn't have to be when you're entering for your trip, and if you get it for 180 days you can then come and go anytime you want until the 180 days is up - just make sure you go back to cancel the TVIP before it expires. I found the whole process to be quite easy, the only hard part being that I don't speak any Spanish. There was one guy there in one of the offices who spoke a little English and that helped. Other than that I just handed people what I thought they needed and smiled a lot. Even with the language barrier the whole process was fairly quick and easy.