I certainly don't have all the answers to your questions. After looking at some of the parts you've linked to, however, I'm of the opinion that most if not all the parts your going to want to make will need cnc equipment. Most heli parts [at least the heli's I've worked on and flown] are relatively small in size. Therefore huge machining equipment shouldn't be required.
I would think that a 4 axis system at the least would be needed. If you do go to a 4 axis system, it will have to be cnc, there isn't really any options there. I would say that most of these parts would be best served by using cnc equipment. There isn't any that I saw on your list that would be easily done w/out it [ at least they could never look as nice w/out cnc]
I think your best option would be a cnc lathe w/ a 3 axis mill attachment and a positionable 'C' axis [ the lathe axis that turns]. Also investing in some casting of alum parts would make some of your projects much simpler, you'd only have to finish machine them instead of cutting them from a ruff billet.
Also worth mentioning is that your going to have to be very efficent if you want to compete w/ the listed prices on that website. For example, the last link show's a tail rotor blade holder w/ pitch links. This is made from 3 basic parts, two of which are identical. Each of the blade holders would need at least the following setups.
1) Turning to the proper O.D.
2) Turning the bearing housing parts and making sure to get the proper fits.[two setups due to the orientation of the bearings]
3) Finish milling of the 'Arm'.
4) Drilling the center hole.
5) Drilling the blade mount hole and tapping it.
6) Milling the blade grip's [or whatever the proper term is.. where the blade sits in.. that milled slot]
7) Finish milling the end face [ so its round like the one shown]
8) Drilling and tapping the Linkage ball mount hole.
[that might not be all in the proper order either..]
This would need to be done twice.
Then you need to make the center housing, which would have 4 bearing fits and two drilled and tapped holes for mounting the blade grip housings.
Finally the whole assembly should be assembled and balanced..
Thats all fine and dandy.. but to do it all for $20... thats a tall order..
Even if your time is only worth $5/hr.. and the mat'l was free.. I think it'd be tough to break even.
I'm not trying to discourage you from going ahead w/ this, just to shed some realistic light on what it's going to take. Over time you may get all these process's down so they are all automatic via Cnc, but doing it manually would be a nightmare.. if its possible at all. Going the cnc route, you might get it down to where 1 of these blade grip's is getting cut faster than you can assemble the completed unit. The only way to find out is give it a try .
Hope that helps in some way..