Great tips, let me try and add to them a bit.
1) I agree. I usually start super loose and only tighten a bit if it skips a tooth or has round corners on parts. Mine don’t really make a sound if plucked.
2) Those 1.75″ bolts are on the Middle Joiner parts. A 2″ will fit on the middle end’s.
3) Sorry. The larger one usually fit the longer coupling nuts if you choose to skip the spring anti-backlash contraption.
4) Agreed. Those spring couplers aren’t the best idea, but they can be made to work if you add a washer like the speed washers on the roller f’s and seat the coupler against it and the bearing but they you still get the “up” spring. Rigid is better, or a spider coupler.
5)I’ll elaborate and say make sure to use endmills, not router bits. There are mills for every material and they should be used makes a huge difference. I finally got wood mills and they leave a much cleaner edge. Google single flute vs 2 flute, upcut vs down cut, wood vs plastic. You can save a ton of money getting them from drillman 1 on ebay, they seem very high quality and brand name. http://stores.ebay.com/carbideplus/ I have no affiliation with him, although I wish we could work something out!
Your cuts look great. Thanks for sharing your experience.