spell obstacles and forte tests

[gooderguy]

some of the spell obstacles can climb pretty high, especially when casting hastily.
1. from my understanding, casting a spell hastily does NOT increase the difficulty of the forte test. the forte test is made at the same obstacle as the original spell, correct?
2. i'm sure this will be cleared up in the Magbu but i'm wondering if using an abstraction to increase say, the area of effect increases the forte obstacle or just the casting obstacle
3. does the double obstacle for the practicals when learning a spell also count for the forte test, or just the incantation obstacle?
4. mage light has a scalable obstacle but is not a ^ spell. does that mean it is a ob 10 forte test to call forth the light of the sun? = sudden death from tax.... i have some player's planning to use it to ward off some orcs. probably not gonna be possible without some amazing rolls, is it? even with the x80 actions for + 5D of carefully and patiently - a 3200 action (5+ hour) spell - their chances are pretty low. that's only 15 dice on an ob10 sorcery test. only 10 dice on an ob 10 forte test. if they don't get all 10 succesess, they take a B10 wound? that's kinda intense. am i missing something with magelight?

[luke]

1. I don't have my BW with me, but I know the answer is in the book!

2. Magbu 171-172. Yes. Increases the whole enchilada.

3. Casting and Tax.

4. Yup.

-L

[stormsweeper]

1) Casting hastily increases the tax test by one less than the spell obstacle. See p.221 of the brown book.

2) It's like a major miracle - you're creating a sun!

EDIT:
1) There's not actual text saying one less, I'm just extrapolating from the list given.