There's a couple differences with the vented and solid heads. The vented heads cut the wind better, but they also whistle in flight. The solid heads will plane a little more, but they are quieter in flight. I'm in agreement with others on here, you just have to tune to what you want to shoot.
I agree with trying to find a used bow in your price range. There hasn't been much change with the engineering of bows in the last 10yrs. Just make sure your looking at longer ATA bows. Archery Talk has a ton of used bows in there classifieds
I agree heavier arrows carry more KE. The only thing your really losing with the heavier arrow, is you"ll have a bigger pin gap. Won't lose much in penetration. You will however have a quieter bow with the heavier arrow setup
You dont lose much performance in a carbon bow. You get a little more hand shock with the lighter bow, but not really enough to be noticeable. It all depends on what feels comfortable to you. If you're just walking to a treestand and hanging the bow on a hook, is it really worth the price for a...
Don't put to much stock into the FOC thing. A good arrow weight(470 grains +), good broadhead , and a lot of practice will do you just fine. Also, 60lbs will work just fine.
All depends on what you want to accomplish. If your not use to the altitude and terrain, backpacking in can be a real strain on you physically. If you have a high fitness level, then i would say backpack in and get away from the mob. I've been going to Colorado for the last 6yrs with my Dad. So...