It's quite a while when I posted this topic, but there is some more information about the shrimp...
They are breeding quite well! I gave my population to a friend, cause she has more space to breed the shrimp.
Still not sure about the specie, but practically all dutch shrimp&crayfish (
http://www.kreeftengarnalen.nl for people who understand Dutch

)forummers are saying that they actually are fernandois...
Well, I'm still not sure of the species, but I can tell you something about the breeding.
The eggs are quite small. Something between the eggs of the caridina japocia (salt water stage larves) and a regular caridina denticulata (like the red cherry or redtail). The newborn shrimp are also a bit smaller than the newborns of a denticulata.
But they grow very fast

I still like to get in tough with the firm who importet these nice looking shrimp to ask where they are from. I asked some people to look out in LFS in the Netherlands for these species, but I've got only one respons, so they seem rare here.
If the breeding go's as well as it now does, maybe we will learn something more about the shrimp (it's a possibility to send some male species to a man who can determine shrimp species in Switserland)