Some newbie questions for ya! I play a newbie named Irving who is a Tryker, currently exploring Liberty Lake

(1) What do the numbers in parentheses mean in the damage indicators? For example, hen casting "Rot Damage 1" on a 1x green MOB, it always reports 32 (64). The 32 is the damage realized, but what is the 64? I notice that on melee damage and in the delve screen for items.
(2) What do I need to raise to be a better offensive magician? I'm level 11 now and only have Acid 1 and Rot Damage 1. I do fairly pitiful damage. When I buy and equip better amplifiers, not much seems to happen. With my melee skills, I ramped up real quickly, and the items were of greater significance. I could kill 1x and 2x blues pretty quickly in the melee tree, but I can barely kill a 2x green MOB now with magic

Thanks and best regards,
Irving