1) armrest tends to be problematic for a good playing positionning so maybe 2) hard to say just like that 3) maybe but it can have other side effect (weight of the guitar on the shoulder instead of the leg, standing up for a long time, etc...) 4) yeah, being overwhelmed usually stress the player which tends to grip too hard and contracts muscle a lot more than what is really needed which will bring pain way faster. 5) relax and take it slow, you might wanna grip too tight which will be a big issue in the long run 6) Hell yeah, the higher the action the more pressure you have to apply to fret the strings the harder it is on your muscle the faster the pain will come But one very fucking important thing to remember : NEVER EVER play through pain! this will fuck you up faster than you can imagine and it will make any more training worthless. Take a quick break if you start to feel pain, 5/10 minutes and come back or just stop for the day. There's no need to push further than what your body can handle and health is way more important than being good at something.