So Vita, correct me if I'm wrong. Theurgy, at it's most basic, would merely consist of writing down the appropriate symbols/words as well as a magic circle (or is the circle optional depending on what's being written?) on a surface while running your mana through it, and activating it by running your mana through it again.

1. Am I missing anything in that other than the fact that more advanced Theurgy would require more ritual components?
2. Do Ofuda use roughly the same process? I assume so, but it always helps to ask.
3. Can I use any old means of inscribing the inscription so long as it's manual? Like a pencil vs a carving, or blood vs ink.
4. Is the Affinity of "Writing" acceptable? The way I interpreted it would relate to Communication, Contract, and Information, if that helps/clarifies anything.
5. Would it be possible to forgo the most-if-not-all ritual aspects and just improvise Theurgy on the fly? And by that I mean something like inscribing a few runes down on the ground as you're bleeding out in a pool of your own blood, or painting one on your face for a quick boost in vision.