You're probably wasting your time if you're looking at an ag school. You'll find some that will tell you that you can go get a job after going to an ag school, but it's a very long shot.
Depending on your experience, I see that Bighorn Airways in Sheridan, WY, was recently looking for a pilot to fly light twins, who could do a couple months in the summer in an Air Tractor AT-301. You might contact them and see if there's a place for you.
I don't know a lot of ag pilots that travel overseas for work. The ag world outside the US is generally more bleak than it is here.
Depending on your experience level, there's forestry work here in the winter, and row crops, speciality work, seeding, or fire in the summer.
Insurance doesn't really care if you've been to a school. You come out with a few hours of supervised experience in an ag airplane...which doesn't count for much. Most ag insurance wants a thousand hours of ag to start. A lot of ag operators are using trubine equipment these days, and regardless of what's being flown, you can't really get a checkout in the airplane. Your first time on your own is your first checkout...done by yourself, and tha'ts a gamble, especially for a new, unproven, inexperienced pilot.
The flying is really the short end of the stick, meaning it's the easy part. The experience goes beyond simply flying straight lines or holding a constant height. Drift control, crop knowledge, an understanding of entimology and plant disease, etc, are important parts of the job, as is a good understanding and skillset of the maintenance aspects of your operation. The ability to fly the airplane and fix it goes a long way.
Drift is a very big issue; mess up a crop or get a drift claim on another farmer's crop, and the operator could be put out of business with the ensuing law suit or damaged reputation..just one bad job can not only ruin the career but destroy the company....and a farmer who won't pay because there are skips in his field, when you just sprayed it with thousand-dollar a gallon chemical, will do the same thing. Think about the risk an operator might take employing you with that trust.
Ag Flight out of Bainbridge, GA, is still doing ag training, I think. If you're really convinced a school is what you want to do, you might check into them.