Free if no oil is involved, use fry light if you need to roast veggies beforehand, otherwise bob's your delicious free soupy uncle! (Hmm, not quite sure where I am going with that )
1 level teaspoon of oil is 2 syns, in the worst case I would say they could have used 2 teaspoons, so count it as 4 syns and you should be okay
There is the whole stock issue but if it is veggie soup I'm sure no animal fats would be involved. Annoyingly the SW website seems to be down at the moment!
At the end of the day it is a bowl of soup not a burger or a kebab so don't fret about it too much