the issue is aim shot takes 3seconds to cast sure i love when i can get it off but especially in 30-39 and 40-49 you are getting attacked alot and some of your best options are to aspect of cheeta+vipersting and kite ppl around all day.
oh and as for amulets there is a +20 attack power one that you can pick up from a quest in theramore island that has you killing rock elementals outside of purple side maradon.
also your question about the dragon scale BP, its kinda up to you, you will sacrifice about 10-15 agil probably and maybe 2-3 stam but you gain +13/fire/frost/shadow (GG mages/warlocks) and a 600 dmg magic shield. which could be nice it is going to come down to how you want to play your hunter.
the 13 resist isnt going to make or break you that much especially since alot of the ppl doing WSG have the -10/20 resist trinkets. (i stack them on my warlock). but that does add up when you get some resist gear/enchants like that spread around your gear sets. so if you had that BP/ the +5 that is 18 to those and dwarf has a nature +10 frost so you would have 28 frost. sure doesnt seem like a huge thing but it can up your chances to resist by a considerable amount.
also you asked about a build. if i was doing 40-49 this is what my hunter would have
http://www.worldofwarcraft.com/info...000000000000000510510305100000350050510000000
you get all the important things from marksmen, and the survivability that mean 60's look for from survival.
only thing you may want to change is the survivalist into entrapment and maybe take 2 out of humanoid slaying (yes it works in PVP according to the hunter forums) and put it into trap efficency.
having a freezing (aoe slowing) entrap like 3-4 ppl that are chasing you in WSG is priceless.
but again comes down to play style and how much you honestly are spamming traps.
