Greeting from the Olde North State, and welcome to my first CNC router build. This will be an all steel welded table with a 5hp ATC spindle (hopefully), Clearpath's or servos, linear rails, and rack and pinions . The plan right now is to have the gantry and frame machined at a shop (TBD). This will be a machine for cutting out cabinet parts primarily. I have been learning Fusion 360 for the design, and decided to start with the Z-axis and build out from there. I'm planning to buy the motion parts from Automation Overstock, but I am open to suggestions for everything. I'm looking for good value readily available components that could be upgraded later if possible.

Some details on the Z:
BLH 20mm guides
20mm x 500mm rolled ballscrew (5mm start)
245mm of travel
Z is 200mm wide
Gantry beam 6" x 10" x 3/8"

Questions:
Is a 20mm ballscrew enough to handle 100 lbs. ? (spindle, plate,rails,srcew)
Micro switches vs proximity switches? Proximity switches seem to be problematic.