Simple Q&A D&D 3.5 (by RAW) XXIII

[Corinath]

Q 384

If I'm hiding behind an unaware enemy, and I UMD a buffing wand (Like True Strike or Wraithstrike), does the enemy become unequivocally aware of me at that point? What about a Casting Glove? Wand Chamber?

Edit: Had one more question.

Q 385

What's the equation to find out the price of a continuous use magic spell on a weapon/armor? (I remember duration of a spell had something to do with it...)