Firstly I as looking at the 90 cm light bar with Z holders. I understand the light bar is actually shorter that 90cm? Or is 80cm light bar better?
The lightbars are slightly shorter than the named lenght, but a 90cm bar will not fit in a 83cm cover, so I am aware you have to use the 80cm types.

Secondly I was looking at using a actinic & deep actinic. Can these be mixed and still controlled together ? Eg light intensity & mix of colours?
No problem at all. If you do so, you have 8 channels instead of 7.