I figured the field school would provide the AAUS training, and it is likely to be quite tailored in terms of having a heavy focus on skills you will need to do science underwater. One of our members here on SB, Thalassamania is an expert on training AAUS divers, so you might drop him a PM. He may also have advice in regard to equipment. I also think your field school will probably give you lots of opportunity to build up your dive experience as Stewart is suggesting. And it's a given that the people training you and working with you at the field school will be able to tell you a good deal about institutions, degree programs, employment/volunteer opportunities. I think you're making a good first step! Another one of our members here, BurhanMuntasser was recently asking about programs like this, so he may have gathered some information that he's willing to share as well (I think he wants to develop the field in his home country). Best of luck to you!