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?

Well, for spell resistance you were doing it right before.

After the spell resistance test, there is no additional body test to sioak damage. If a mage casts an S manaball on you, and after his sorcery roll and your willpower roll to resist he has 2 net sucesses, then you take a deadly. No more resisting. Deadly. do not pass go. Die.

The attribute is called "Body" in English.

I have never heard of people inserting a separate Damage Resistance Test between the Spell Resistance Test and Spell Effects (phases 4 and 5 of a casting a spell, SR3 p. 181) before. The intent of the text is definitely that you aren't supposed to roll a Damage Resistance Test in addition to the Spell Resistance Test when targeted by a Combat Spell.

For example, it states that with Elemental Manipulation Spells the Spell Resistance Test is actually a Damage Resistance Test (with Combat Pool and all). If you were allowed a Damage Resistance Test in addition to a Spell Resistance Test with Combat Spells, it would instead state that with Elemental Manipulation Spells you just don't get a Spell Resistance Test.

That is the correct way to interpret it. No double-dipping for the victim.

Of course, that makes it very all-or-nothing for the caster: if the target resists, no damage at all rather than reduced damage.