I use bev seal ultra, but a different size than what you will be getting. I would highly recommend getting the John Guest shank fittings as well as the quick disconnect fittings. They are amazingly easy to work with, just a bit pricey. Amazon sells them in bags of 10, roughly $40 for the shank fittings, and $20 for the quick disconnect fittings.
I just finished updating all my faucets over to the 650ss faucet to unify, as well as to increase restriction dynamically as needed. I am using 1/4" ID bev seal, which has a restriction a fraction of normal line, and I didn't want to use 50 ft per line, which required me to use the 650ss faucets.
With the 3/16" ID line, I would personally recommend starting with more line if using non flow control faucets. When I had PVC lines, I used 10 ft of line per faucet to balance as I desired with regular faucets. Using the same mentality, I would probably start with 20 ft of the 3/16" ID bev seal ultra.
If you decide to go with the 650ss faucets though, the line length doesn't really matter. I even built direct keg serving setups using the 650ss faucets, and can pour directly from the keg.
The tubing is considered semi-rigid, and really was designed to use with the John Guest fittings. For me, the reason I went with the 1/4" ID was because I had already been standardizing to 3/8" OD tubing and John Guest fittings for that, and didn't want to rebuy all those fittings, so I needed to go with the 3/8" OD Bev seal which had 1/4" ID. It clicks into place nicely, and is very quick and easy to use.
If you balance the lines properly, you don't need the 650ss faucets, and I would probably go with the new ventmatics which are about the same cost as the 650ss faucets.
Show some pictures when you are done!