USMCFLYR,
The helicopter guys are mostly concentrated out in California, Arizona, with some helicopter work being done across the U.S. As far as the night flying, that too is mostly concentrated in Cal. and Arizona. I think a big reason for that is because they have lots of problems with the general public fussing about the airplanes flying around the house. Also, they raise a lot of bees in those regions, and need to get their spraying done when the bees are in the hive's.
Ag Aviation, as a whole is so far advansed now than even ten years ago that is is rather mind boggling. The chemicals used today are much more "user friendly", The airplanes are no comparison to what we had years ago, as far as safety, productivity, and efficiency. Of course, with all the improvements the price went up on the planes. A new 802 Air Tractor is around 1.2 million or so. My first plane cost around $25,000 new in 1975.
Also adding to the "new" image has been the programs designed to increase safety concienceness in the pilots themselves. We are required to attend "recurrent" training yearly. This usually amounts to a day or two of meetings where the topics range from the lastest chemical products and how to safely handle and apply them to analysis of accidents that have happened. Points being stressed to avoid previous mistakes.
Todays ag pilot/operator has such a personal investment tied up in his or her business that is is in their best interest to do things right and try to keep the spotlight off him/her as much as possible. I heard a very cocky new guy say one time that he loved to "raise hell" in an airplane. The old grizzled veteran ag pilot looked at him and sais, "son, don't go looking for hell cause it's gonna find you quick enough in this business. He was telling him, Don't be a cowboy.
Good luck out there.