This thread really should be in the tactics section. Other than that....
The only way to really up your magic is Vampires with Dark Acolyte. That costs some close combat powers so it really is a trade off one has to balance. VC are stuck with it and if your opponent has heavy defense you either have to go heavy or bring just enough to stop the game changing spells.
Magic in WFB is just odd. Sometimes it is vital sometimes just a distraction between charges and CC. The last game I played only had one spell go through without dispel and that raised a single grave guard with great weapon. Had other games where a unit over forty zombies was raised. Very Rarely has it practically won or lost a game by itself.
If you want to let the hit your flanks that's okay if you have lurking counter chargers like Cairn Wraiths, Black Knights, or vampire on a monster.
Grinding ahead is perfectly valid too. In the last book VC were pretty much forced into tight unit formations except for Ghouls and Fell Bats. Odds are overruns against you won't happen. Undead don't panic like mortals, they break with enough pressure but it isn't a simple task. If most of your army is rank and file then a few ellite units of CC Elves shouldn't be a threat if your units can cover each other.
The Archers don't like Fell Bats getting behind them. Might be a time those direwolves wouldn't be so bad. Presuming they didn't soak up all the fire first. Anything ethereal like spirit hosts moving up will get you a reaction. The Vangulf(sp) doesn't like massed arrow/gun fire so don't make that mistake, trust me. Black Knights can tank the fire and force them back or charge for an overrun.