1) If it is not an attack spell, do you see correct to use the 'E' column in fumbles (for RMSS/RMFRP)?, we have that is the worst column, so using it if you fumble starting a fire, I see it excesive. Do you see correct using the non-attack spell column?.
2) Initially we have no RR for these spells, so how about casting some spells, like firewall or stone spikes, over a target?, in this case what is better, allow RR, don't allow to cast the spell in that manner, or simply allow cast it because the effect is balanced (it is only 'A' critical, usually the critical is low for the spell level), in this last case you always can use the target skills, maybe using QU for evading the spell if target aware about the casting against him.
IMO the last one could be the best, it doesn't break any rule and uses the characters skills.
I'd like to know other opinions.