Alright, I'll help you out a bit here.
Every skill that is based on Weapon DPS gets stronger with points into strenght. Focus does not work directly on DPS based skills, BUT, if lets say you deal the percentage of weapon DPS as an elemental damage like fire or frost, focus will raise that damage. Focus also raises of the DoT(damage over time) of skills
You definitely need to be putting points intro strenght if you want to use auto attacking most of the time. Strenght raises your weapon DPS and gives you a higher % of critical damage. Focus gives you more mana, more elemental spell damage and a higher execute chance. However the Zerker has the skills executioner, which raises charge rate and execute chances significantly (Only affects you if you are dual wielding).
I would definitely say str>focus as an normal/auto attacking zerker. The extra DPS and crit dmg is very important. However focus is a good stat, I'm not entirely sure how or when it becomes relevant. I would say if you make a caster zerker, focus is the better choice.
Attributes on weapons that deal something like 1000 physical over 5 seconds does NOT count as or add to weapon DPS.
Regarding builds, check out this thread:
http://forums.runicgames.com/viewtopic.php?f=44&t=39820