Hello Mr. BuildsToys. You should start by joining the Chromatic Dulcimers Group here at FOTMD. There you'll find a smaller number of people who actively play and build chromatic dulcimers. Out here in the general forums you mostly find blowhards like myself who answer questions even when we don't really know the answers.
I"m sure there is a learning curve if you've been playing a diatonic dulcimer and switch to chromatic. Just adding the 1.5 fret took me a while.
I know Erin Mae Lewis regularly teaches online workshops for chromatic dulcimer and I think she has a book out as well. But the folks in the Chromatic Group will have more suggestions for resources, I'm sure.
As for position dots, I think there are two options. The first would be to put position dots in the same spots as you would for a diatonic dulcimer, meaning 3, 5, 7, and 10. The other option I've seen much less often would be to put position dots on the diatonic frets to help differentiate them from the chromatic frets. I would express my preference, but since I don't actually play a chromatic dulcimer, I would just be guessing anyway.
Dusty T., Northern California
As a musician, you have to keep one foot back in the past and one foot forward into the future.
-- Dizzy Gillespie