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My wife and are are close to running the first files on our CNC. What basic router bits should we be using?

It depends on what you are cutting. My biggest usage is making MDF router templates so I use a 1/8" bit for cutting them. I use a 1/2" or 3/4" for leveling the scratch board. I use a 1/4" ball-end when doing fretboard contouring. I always get solid carbide. MDF dulls even those pretty quickly.

It really depends on your machine and the job at hand.
My machine is limited to 10,000 rpm and has a hard time getting above 200 FPM.
I get best surface finish across the grain at around 100FPM

Pay attention to speeds and feeds.
Most hardwood has a surface feet per minute SFM of around 2000.
Chip loads vary with bit size but those provided for aluminum seem to work well.

There are lots of speed and feed calculators available just do a search.
CNC cookbook is a good source.

I go all carbide as HSS will dull quickly if the cutting speed is off.
I like uncoated 2 flute carbide spiral end mills rather than straight edge router bits.

My general purpose bit is an up cutting 1/2" bit and I use down cutting bits for pockets.
I use a 1" straight edge ball router bit for shaping and 1/8" down cutting and smaller for inlay and tight radii.

Peter gives solid advice.

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services