spell damage resistance Options

[Inferno]

I´ve recently discovered that my new SR 3 playgroup handles spell damage resistance fundamentally different then my old one: We always did it like this: Sorcery test, spell resistance test, stage damage with net successes (spell only successfull if caster has more successes) and that´s it.
In the new group, the victim gets a seperate damage resistance roll, using constitution, AFTER spell resistance.
I´ve read the rules on this carefully, and, as far as I can tell, the do not say explicitly which way is correct; a case can be made for both.

My questions to you: Have I been to blind to find the relevant paragraph? How do you play it? From a game-balancing view, I think that the "new" way puts even more emphasis on the already uber constitution attribute. Comments?

On a completly different note: I´d like to make a spell that paints an image from the casters mind onto an apropriate surface (If my master allows it. He might have concerns about instant-hermetic circles... just add water, err, mana ;) ).
A physical manipulation spell, obviously, but I have no clue what kind of drain TN should be. Is this a (descriptions taken from MITS) "minor physical change", a "major physical change" or a "minor enviromental change? Also, is this an area effect spell? Does this require "fine manipulation", which would give it a TN of 6 instead of 4? Should the duration be "instant" or "permanent"? Finally, what effects would would more successes and/or higher force have?