I think it is very comfortable. Not as comfortable as my Xbox Series Controller, 360 controller or my PlayStation 5 controller but definitely very enjoyable to use. There was an adjustment period, especially to the analogue sticks. The weight is there. I don’t hold the deck with my arms fully extended so usually rest my arms on something. Like my lap, stomach, sides of the bed. You should be able to figure out what works for you once you have it in your hands
Yes. In Mini Ninjas for example, if you force any other version of Proton other than the default, you will have no sound.
Unless you are experiencing issues right from the start, it is best not to force any specific version of Proton.