its not a must but my suggestion...
For jewelery molds you would need rather fine resolution but also small dimension on the axis - no play on the thread nut combination and prett good precision -.. I at least would go for IT 5 Ball threads ( 23micron per 30mm length) with preload on the nut so you can physically avoid the reverse play .
thread height and diameter should give you the possibility to semi step increment the movement to physically 0.01mm.
the 4th axis should be supported with a self locking transmission without play
and a also very fine resoution ... perhaps you could google for "Harmonic Drive"... a metal flex transmission could also work but supports no full turn on the A Axis..
Regarding Cam ... a four axis simultaneous CAM wold be rather high effort
renting a license may come up to several thousand bucks a year....
for working wax you would probably need pressure air for cooling and a rather small and light high speed spindle ....- for larger aluminum parts you would need a larger and more powerful spindle... and all the structure would have to also be stronger ... Dont know, if both materialsin one target would raise the costs of the router.... ( one material is to be worked very precisely and the other one is harder to work with and rather rigid)