A CNC machine like the Nomad is accurate and precise to 0.001" (one thousandth of an inch). The machine far exceeds what conventional wood working expects.
When one machines, the most common approach is to rough (cut away quickly) most of the material that needs to be removed. The roughing will leave a little bit of material to cover the shape that one wants when the works is done.
The depth of the layer left after the roughing is set to ensure that the fast cutting never damages (touches/tears/gouges) the surface of the ideal object embedded within. We’re talking 0.010" or less.
One then finishes - go slowly, careful, and with great concern about the finish - the object, removing the small amount of material that the roughing left. Obtaining the finest finish doesn’t necessarily mean going really slow… just (much) slower than roughing. With care - often by performing some experiments (what we call feeds and speeds tests) - the finish will be pretty darned good for a nice block of hardwood.
Any tool marks - “ripples” left in the wood that cause the desired surface to depart from the perfect - will be very small indeed. If any sanding is necessary - and that will vary with the wood, the geometry of the part, and the machining choices - it will only require a very minor sanding (a very fine grit) because the machine has done it’s work to levels much smaller than conventional wood working is capable of.
I did a Steampunk case for the modulator (controller) for a Tesla coil in Red Oak last year. When the cutting was done I could just barely perceive a few tool marks. Less than 5 minutes with 180 grit sand paper and all of the wood was like glass.
Acrylic - I prefer polycarbonate but YMMV - can be machined to near utter perfection in the two passes however to do so will entail the use of tools (end mills) specialized for these materials. I’m talking near glass like finish. A good job can be done with conventional end mills but that amazing finish is bet obtained by using the right tool for the job.
Since you’re new to this, use the forum to ask questions. Be sure to work through the initiates exercises and read up on CNC.
This is one great place to read up on things CNC: http://www.cnccookbook.com
The G-Wizard (feeds and speeds) and GW-Editor (G-code simulation) found there are some of the finest helper software for machinists that I know of.