Primary Stats, Armor, Damage Reduction, Dodge and Crit, what are their optimums?

[reyals]

Yes i see that too as Str build with hex is a pain to proc.

it's same chances to get proc with any build (flame and immo staffs), easiest way to check flame staff - farm jewels in maus (having witch debuff ofc)
both staffs procs works in 2 steps:
1) getting proc at target(s) only by autoattacks (immo staff normal/charged, flame staff - only normal attack)
2) hitting that target by attacks/skills (flame staff - hitting affected target will cause more fire ticks at current target and chances to spread, immo staff - after 10 hits target will get damage with chance to deal aoe damage and chances to banish, your partymates hits counts for both staffs too, pets - im not sure)
damage from flame and immo staff (if it didn't banished and only dealt dmg) depends on your DMG stat (maybe it was reason why you think that it's pain to proc with str)

How come primary stat increases dragon staff proc chance? What they changed about proc was different. Actually primary stat increases proc dmg, not proc rate.

Primary stat doesn't increase dragon staff proc dmg, it deal damage depends on enemy max HP and can be increased by %dmg %ed %bd (and decreased by some things...), your INT or base dmg doesnt affect it. For example you can get trash gear and have 1k dmg but 100% bd VS high dmg gears but 0% bd, you will see what deals more damage by drag staff proc (same about procs of balanced staff/immo bow/duggar bow, but duggar proc also can be crit, so need to have high crit also). It's how drag staff works after last change (at lvl71 expansion), before that change - damage from drag staff proc couldnt be changed, and was based only on enemy's max hp