Nitrous and Ignition Retarding
 

From what I have read, engines running Nitrous have their ignition retarded, now much I don't know. If this is the case, do I need to retard the timing further on starting to preclude kickback?

No the Nitrous has nothing to do with the startup timing.

If you have a lot of compression etc an MSD ignition can be set to retard enough to make start up easy and then return to normal retard at 1000 rpm.
Nitrous retard shouldn't come in until the nitrous is activated, through the MSD.