Just want to add that you should check out your local ranges that shoot 3gun cowboy and go from there. You could end up with more stuff than you really need to compete, not that is is okay.
I shoot action pistol at deadwood boys a lot as there are two matches a month, some modern rifle, some modern 3gun all at the local range.
SASS has my vote for most fun with nice compadres.
I guess you are going strong side rather than cross draw. I like my holsters where my hands fall=at each side. Some guys I shoot with like them closer together (they shoot much better than me). +1 for trying both on a timer. Try them two fists apart as well. On the belt, I like a belt with a width that matches the loop to take up slack. Notice the holsters are meant for speed so the pistol rides high so you can grab it and get your finger in the trigger guard quick but the draw back is running fast between stages the pistols can come out sometimes so check out the retention factor by play running between stages. I would chop off the extra length on the tail end of the belt so you do not have to tuck it behind the left hand holster. Help it helps a little and welcome to cowboy!
I think cap and ball are not on the ship to ffl list here. For cowboy guns, never had an issue with a FFL to FFL shipment to California. With modern stuff, if its on the no no list ( even a gen 4 glock), its an issue.
In SoCal crossdraws outnumber strongside. I shoot strongside and I think it takes longer as you transfer your weakside from one hand to another. Pretty strict here on the 170 issue.
I use the bullet cardboard boxes for bulk, sharpie with bullet type and grain, powder type and grain. Sometimes mark it as pistol or rifle. I load the cardboard boxes up for matches and shake them out into the pouch by the tens.