hey Samy, your build is looking really good only i have one suggestion or tip.
From where are you gone power that weapon shaft where the disks are connected to.
What are the sizes of those bolts that hold the disks. I know from the past even in smaller weight classes those bolts can easily snap off if you still have possibility you can maybe use shoulder bolts to connect those disks to the center hub.
To your First question, I´ll use Belt Drive, you see the Grooves at Pos. 1
To your Second question. Pos.2 Nope, i dont use normal Bolts or Shoulder Bolts because I think its a bad Idea to tighten it to the Aluminum Hub.
As you can see, the Cylinder Bolts go all the Way throw the Hub and are tightend on the Other Blade.
This has a lot of benefits for the Construction. First, both Blades are connected. Thsi is much better for Energy transfer than bolted directly to the Hub. Second, you can use more torque than tighten it in Aluminum.
And Third, if a Bolt will snap of (which never happend to me before, and Scrapy 1 also used this construction) you just push the old bolt out with a rod and add a new. Try this when a Bolt is snaped of when threadet directly in the Alumium. Easy maintanance is very important for me.