Hi,

is it possible to reference nodes?

Sure, just goggle it if you want more info.

If you want to instance a network, you need to make an HDA out of the network that you can use in your scene multiple times.

If you want to instance geometry on to points, you can do that with the instance object, the copy sop, or using packed geometry.

Not sure exactly what you mean, sorry.

Instance vs. Copy
http://forums.odforce.net/topic/23294-houdini-16-wishlist/?do=findComment&comment=143811 [forums.odforce.net]