My UI is a mess so I can't advise you on hotkeys and the like. (For me 1=Iceblock, which you don't have yet, 2=fireball, 3= scorch, 4=AE, 5=DB (was CoC) 6=fireblast 7=poly) However, a few basic PvP tips, many of which you may know:
Avoid casting anything longer than 1.5 secs unless you've already got someone sheeped or you have the drop on an opponent. A pyroblast is an invitation to be silenced/stunned/feared but so is a fireball. Basically, use almost only instant casts, scorch, poly and rank 1 fb (to slow) in face to face combat. I usually only use Arcane Missiles if someone is trying to los me because the missiles follow the target even if it is out of range or los.
Focus on spells that ***** with the other players -- ie, FN to hold em in place, CoC and BW to slow em down, sheep liberally, counterspell when you see an enemy casting (but counterspell the right school -- dont cs a lock's shadowbolt, cs his fear. Don't cs a druid's roots, cs the regrowth). And so on.
And have fun, don't stress about dying.