Here it is.
1. What training does a career in forestry require?
That will depend on what you want to do within forestry. You can get started doing timber stand improvement work or fire fighting work with very little formal education. (basic firefighter for USFS requires a 3-5 day class. many states would require even less).
I have a Bachelors, and would recommend that if you are strongly considering a career. It opens the door for more opportunities and lays a good foundation for lifelong learning.
2. What natural abilities or interests are needed for a career in forestry?
I think the biggest need is a desire/interest for being outside. I also think both forestry and arboriculture are best fit for "logical" thinkers rather than more "abstract". Both can find plenty of career success and enjoyment, but that natural thinking pattern seems to be common in the field.
3. Is there good job availability for those who choose forestry?
Traditional forestry as a forester...job markets are a little tight. Looking to be in arboriculture or logging...plenty of opportunities if you are willing to, show up, work your way up and work hard.
4. Would you rate the opportunities for advancement as poor, fair, good, or excellent?
Excellent opportunities for advancement for those interested. I say this because most of us enter these career fields because we like to be outside and get our hands dirty. Much of the advancement opportunities mean more time in the office and less time in the field. A good field technician who is also good in the office and willing to take that step will always, I believe, find opportunity because so many others like where they are too much to spend more time in front at their desk.
5. Could you list a particular advantage of being a forester? A particular disadvantage?
Advantage: job enjoyment. Working outside, job variety, working with so many different clients are all great parts of the job. Disadvantage: pay scale. (not that there aren't foresters who do very well, but when I look at what other professional degrees, like an engineer, make...foresters aren't there).
6. Are there any current problems faced by most foresters?
Largely depends on where you are and what sector (public, private, industrial) you are employed in. But I'd say it is not a field that garners a lot of "pubic respect". Read a list of articles about forestry practices, harvest planning, wildlife management (or even agriculture for that matter) and you will see a list of people with no education in natural resources convinced they know more than the trained and experienced managers.
7. Do you have any special advice for someone interested in forestry?
2 opposing roads:
A) Go for it...I have enjoyed the ride so far. I really enjoyed studying forestry in college...and I am not sure studying a field I wasn't so interested in would have gone well. Something had to motivate me to put in the hard work.
B) Be a dentist. I have a few clients that probably spend more time in the woods than I do. One of them is a dentist (owns his own practice) and he told me once "I leave the office every day and am in the woods by 3:30 and all weekend." Told a colleague about that and we laugh...maybe that is the best career advice we can give 
Thanks to any and all who are willing to help me with this portion of my Vocation Project!
