Also be aware that just because you pass the school, you still don't have any dive "work experience". You will have weld expereince, but not alot under water only training. You will start out as a tender/ red hat. That's how all the new guys start, so that you get some experience with the gear and equiptment and how to operate it. I'm not talking welding machines, I'm talking compressors, dive chambers, hard hat maintence and such. Being older and more mature( i'm asuming here) will work to your advantage, because most new guys are young and cocky, but they can also carry the load easier than some us older guys.
I did it for a short while 10-12 years ago, although I didn't go the welder route, I was an underwater inspector. We didn't have any inspection jobs so you go out and do any other job that comes up, looking for pipe lines, changing out valves, locating lost equiptment, whatever needs to be done, if you are a diver you'll do it, sometimes they'll need a welder and you MAY go on that job, but remember the bigger outfits have lots of other people already so you'll be at the end of the line.
Most of your time will be offshore, away from the family. Sometimes on a small 100' boat, sometimes on an oil companys rig with direct TV, it depends on the project. Unless you dive deep, thats where the big $$ is but the gulf is not deep unless you go WAY out. But again, there not going to send a new guy down on a deep job in the beginnning, your going to have to prove yourself, and stick to it.
If I were you, I wouldn't do it after having been there, but thats just my opion. Don't listen to all the info the schools will tell you. Higher education these days is a business. There commodity is education, thats what they sell as opposed to TV's or groceries. I don't think they will lie, but they will embellish as needed. They want you to go thruogh their program and make money. You should contact the dive companys themselves and see if there hiring first, ( because with oil prices down they don't do alot of maintence) then ask about the rates and healthcare and what sign on bonuses they may have. When you talk to the schools they will tell you what companys they work with in the gulf.
Good Luck, Chris