Don't go 120 dex until you're 150 I would say, until then, deal with your slow cast - it should be fine versus smaller MVPs that you won't always have to crush to win (moonlight,orc hero, phreeoni are good leveling ones)
I would say get a +9 Immune HBP for defense and added stats when you get 90's of STR/int/dex as well as a decent weapon. I think right now your 200m should go towards a +9 red twin edge (try to get one for like 100m) and put 3x AS cards in it or buy one with them in it. That weapon will alow you to bomb those mvps easily as a biochem.
The ideal enchant for dex boots is EA4 (no need for spell enchant, since your cast time is going to be dex based primarily) and for the special enchant Lucky Day is very versatile, bears power is great for tanking MVPs to boost bomb by a TON, and Runaway magic for when you're a high level gene and want to use Demonic Fire to proc the +200 int for CC.