Can you add in the Interactive (-i) flag that CudaMiner has? To make the miner not take up 100% of a cards performance?
-i is already there. Max range is mostly around 20 (-i 17 already gives better control over your desktop), but you can go higher. It will crash if you reach maximum

He's working on specifying it per gpu, ATM it's per ccminer process (so just run 2 ccminers, switch with -d 0 -i 17 and -d 1,2 -i 20)
Also would it be possible to add in Scrypt and possibly Neoscrypt? I know Nvidia doesnt do these very well, but sometimes i mine just to heat the house at winter (many others too!)
Neoscrypt is in the works
https://bitcointalk.org/index.php?topic=916336.0But why would you want scrypt? Need electric heating?