RE: Young hunter looking for some answers
The legal minimum for a bow here in NY is 35 lbs to hunt deer.
While I think this is a little light, 40 - 45 lbs will definately kill a deer if the right broadhead is used.
That being said, I would limit the distance I shoot to what you can comfortably aim at with little drop in the arrow (20 or so yards is probably a good first guess).
Also, be sure to use very sharp (cut on contact may be best) broadhead that is NOT mechanical. Mechanical heads need more energy to open correctly upon hitting the target. I would recommend a light Muzzy head or a 100gr NAP Razorback. I have little experience other than with Muzzy, so maybe someone else can answer this portion a little better.
Anyway, if you start shooting now, you will be suprised by how much strength you gain by next year. Just have to get out and practice practice practice!
Good luck!