Yes, 15 GPM from one set of couplers. If the loader has sizeable cylinders, 15 GPM is rather slow for me.
A CCLS valve will require extra fittings, hoses, a shuttle check valve, mounting bracket, etc. in order to complete the package. This has been discussed numerous times here in the past. As for the going rate on a CCLS valve right now, I have no idea. If you don't intend to use the loader much, I personally don't see you getting your money's worth out of that conversion.