It does not seem like I will be able to give you a trial as it is not supported in the current version. I will try and put up some screen shots instead and maybe put together a video.

Can you asign which universe your artnet is outputing on ? and if you have lots of leds fixtures split them up on to multiple artnet universes?

Yes to both questions

Can you assign a control universe of artnet (so control is from say a lighting desk, on universe 0) and led on the other universes?

Yes

Would it be too much to have the possibility of spliting the output, so say you have 1 layer outputing over artnet and 1 layer outputting to a monitor output?
(I ask this as to have 2 pc's and a lighting desk to run a screen and a few leds in sync is alot of kit and I am looking for a compact portable system to achieve this).

It is a possibility for future versions. For the moment you do not need two PCs. You just run two copies on Screen Monkey on the same PC.