No. When I used to give piano lessons, my oldest student was 62. It was something she'd decided she wanted to do when she retired. She learned, too. ;)
No, never, though some instruments are better learnt when young... drums for instance which can be quite physically demanding or the tuba and flute which need good lung strength. Apart from that, there's no real barrier to learning an instrument at any age.
Whan you hands shakeing and cannot hear a thing...
No, studies have shown we can learn musically all our lives, in fact it keeps our faculties sharp. I just turned 58 and bought a harmonica. I have to do something for spare change when I retire ;-)
No, not at all. Till you are feeling sleepy.
If you just want to learn how to play and have a good time with your friends, no. If you want to play in front of thousands of people....yeah there's probably a cut-off somewhere