Does one order the DEFT-EDC from the website or via email or PM? Also, any of the parts of the light SF compatible?
The website is fine unless you have something else you want that is not up there like a red or green LED version. I have had one customer say they could not get their Surefire tapeswitch to work with the DEFT-edc but I ordered an off brand one that was supposedly designed for Surefire and it works beautifully. The tailthreads at least should be Surefire compatible. Haven't tested the head yet but can if you want me to. Better to just have me mod your favorite P60 light instead.
Can I use a C-series typical?
Not sure what your are asking. Sorry.
Any pocket clips work with the DEFT-EDC?
I haven't looked into it yet.
Is the head just modded, thus legoable with other SF parts? Web store shows the DEFT-EDC is out of stock.
The body and the head are modded and tuned to fit as a unit. The DEFT-edc is "out of stock" because I am about to release an updated version. I am working to get at least a small batch out this week. This will not be evolutionary as much as revolutionary. Same basic body with some differences but major performance improvements.