so as the title said here are some things i want to know and still confuse about :

-which one is better, necroptic,magmatic,living armor or ice scale ?
-does frost bolt is aoe based? does taking the aoe upgrade take effects on the skill?
-which one is better? taking the fifth upgrade of the fireball? or take the first uppgrade of the frostbolt for potentially more DoT skills?
-does DoT skill has limits on mobs? (i.e. only 2 skills can be stacked)
-which pets is best for pve? yowie or blinky? yowie has hp upgrade while blinky has crit boost?
-which passives i should get?
-why take 5 skills? when you can dump the skill into passives?
-staff or guns? (stats or damage?)

im sorry for the noob question and sorry for the english