HGMan- Sounds like you've got plans for your life. Add riding a motorcycle on the streets to the list. To the bottom of the list. Once you're old enough and wise enough to realize that it's scary and dangerous as all fuck, then you might be ready. Once you have that and there isn't any part of you that's thinking in terms of "if I total it...." as part of your rationale, you're getting closer. Once you have that and you're in a position to just write a check for your Bonnie, go for it. You might be 30. And you'll be way less likely to become an unpleasant statistic, and to live to share your accumulated wisdom with your kids.
Those fucking cagers will kill you without thinking about it, is what the problem is. Until you've put, say, 100,000 miles in behind the wheel, your instincts aren't well enough developed. Dirt bike skills pretty much don't translate to the street. Out on the dirt tracks, there are no 2 ton hunks of steel moving at 60mph and not looking for you to contend with, and there are no barrier walls to keep you from bailing out of a jammed up situation.
[Me: Had a bike for 3 months when I was 17, had two friends that literally died on theirs after kissing cement on an unscheduled landing, sold the bike. Flash forward 28 years and got my BBlack at age 45. Tooled it around the neighborhood a few times until I finished the MSF class and got my license. I've got 11,000 miles on the Black in 2 years, and I think I've become a better cager for the experience. I think it's funny that on my back roads commute to work, I make better time in my car than on the Bonnie. Not because the Bonnie is slow, far from it. It's because there are a LOT of driveways that come out on that road, and funky angle cross streets, and DEER! Stuff that I didn't notice as much inside my nice safe cage, and that after 30 years behind the wheel. I'm comfortable (I think) with my mortality, but of the ways I can think about going, on my motorcycle isn't one of the desirable ones.]
Good luck!
Oh yeah - the helmet question. Look in the mirror. Do you like what you see? If so, full face. If not.... Think of it this way. You're jamming down the road at 60 (ok, 80) mph, just 6 feet away from incoming traffic moving at the same speed. Some friendly driver tosses a tiny pebble/cigarette butt/hunk of gum out the window and it hits you in the eye/mouth/cheek/ear/head/neck with a closing speed of 150mph or so. Would you like to deal with your body's involuntary reaction to that while staying on your bike and out of oncoming traffic, or would you rather just hear the loud crack as it hits your helmet and bounces off?
Not to mention a full-face has way more room for cool graphics.