Hi pred8tr....
Just my .02.
I recommend
www.newbiedriver.com to get a good idea of what you're getting into. Lots of info.
You didn't say what company you're going with or what kind of trailer you'll be pulling but be VERY VERY careful. Please do your homework and check out a lot of trucking forums to see what is being said about the various companies. I'm assuming you are going to work for a large carrier; you should be aware of both good and bad reports, but take the negatives with a grain of salt. Some drivers who have had a bad experience brought it on themselves (of course they won't tell you the whole story).
If you like being alone this is a good occupation. It's one of the things I enjoy most.
Not being paid during training would be a BIG red flag for me. Doesn't sound good.
If you want to work on again/off again that's something you need to discuss with your employer. Just my opinion, but I don't think most companies would be happy about it. You can find work again easily if you're not too picky, but job hopping every few months doesn't look good on an application. Best of luck to you.