Hi Kay,
My main artwork is in glass and stone but like you I wanted to venture in to CNC routing. Up until August last year I was a CNC virgin :-)
My main use for the CNC is wood routing and certainly opens up a lot of interesting possibilities creativity wise. There was a bit of a learning curve, mainly in the use of the CAD software. I suggest you download a trial copy of Vectric aspire or Vcarve, they are not cheap but they are very comprehensive, If you want to do 3D relief carving then Aspire would be the best (and most expensive) package to go for.
A 6090 size machine may suit your needs but something like a 1212 would give you more flexibility.
What type of wood will you be working with and what thickness as that will give a better idea as to a machine spec.

I am only a relative newcomer to CNC work but turning out a lot of pieces now. There are far more experienced people on this forum that I am sure will offer their advice but if you need any help on what it's like to dive in to CNC machining as a beginner I would be more than happy to help.

Good luck

Al