The typer of protection u gonna wear depends on your build.
IF u are full str u can go garm, to cut on mp usage, and for the increased speed. If u are hybrid u can wear protector , to have balanced phy and mag defence and if u are full int wear armor or protector (im int archer and i use protectors) .
But in the end its ur choice, u can wear whatever u like
The most important skills for an archer in my opinion is anti-devil , 2-3-4 arrow combo, berserker/demon/devil arrow. I use strongbow too but u can pass it if u dont like it. Autumn wind skill is good also if u have more than one mobs infront of u close together. Dont forget to get the shot range increase skill , and the passive for better attack rate.
Imo an archer needs all of the weapon skills available so he/she can me formidable in battle , wheter its against mobs or agains players.
I cannot tell u what build to make or which imbue and force tree u have to lvl up. Its up to you.
Have fun building ur archer
Bow rulez
Edit: When sp farming at lvl16 inside the sronghold, ur skills will be at lvl7. So the only skills u need is the imbue of ur choice at book1 lvl2, the 2 arrow combo and the anti-devil (helps for champs and giants).