DMD, don't be intimidated by the Big Boys. Their bark is worse than their bite, and if you're freezing to death they WILL keep you warm. As a military man you should be used to a good razzing: the trick is broad shoulders, thick skin, and the ability to give as good as you get. Some people only respect you if you can match them belt for belt ;o)
As to tree-work as a trade: it's so fun, it oughta be criminal. And I suspect that's the reason that keeps guys in the trade especially when there are easier ways of making the same good money. That being said, it's also brutally unforgiving and it does not suffer fools at all (this is up for debate: please youtube Mike The Narcoleptic Tree Guy). But also, it ain't rocket science, though scientific it is.
It does not take a year to learn how to drag brush across a yard and stuff it into loud, dangerous, clattering hole that goes NOM NOM NOM. Any moron can do that, and that is why there is such a high turn around in groundies: even morons get tired of making less money than they would on an assembly line, or dealing crack. And they get tired of their perpetual sore neck and the bosses justifiably yelling at them.
I would venture to say that it would take about two weeks of dedicated training to learn what you need to know: after that, it's the daily application of what you learn that makes you proficient and eventually efficient; not "fast" 'cause speed kills. That is where the 1 to 2 years of training is coming from. In all of this keep in mind that the day you stop learning is the day you die: and then it's day one of kindergarten. What is most difficult about ANY trade, is what to charge. Tree work is NOT an easy buck. You earn every bloody penny.
The Depression has EVERYONE protecting their revenue stream; competition is no longer viewed as healthy, but as a cancer. And in some cases they would be right. Especially in an era where laid off Fraternal Order-men, collecting full unemployment for the 4000 week, are gladly undercutting their self-employed "brothers" for half the industry rate. This is just a current fact of life. Deal with it. Thrive in adversity.
But if your objective is to provide for your family, make an honest profit, and provide the best Service possible, then let nothing stand in your way. If the only way to get there is to lie (or not volunteer the whole truth) to a company man to get a job so he will teach you, then that is a choice you'll have to make. But keep in mind that "they" invited you to.
If you're serious about arboriculture then inform yourself; learn everything you can about trees, not just how to cut them down, but also how to make them grow, how to save them, when to cut, and when NOT to cut. When to tell a homeowner to call a hack because you don't do that.
If rope and saddle is your goal, then read Fallers Logging Safety by Oregon Fatality Assessment and Control Evaluation (PDF online, can provide the link) and then On Rope, The Tree Climbers Companion, and TCIA's Best Practices for Rigging in Arboriculture. After that, To Fell a Tree by Jepson.
Be prepared to spend $3000.00 JUST to get into the tree safely. This doesn't include "chip" truck, trailer, chipper, stump grinder, or felling and bucking saws.
Good luck to you, Brother.