Best new thing, in my opinion is the dropper post.
I have 26″ and 27.5″, 2×9 and 2×10. I just like to ride.
As far as the clothing goes, I quite like sport specific clothing. I wouldn’t go jogging in my jeans. Yes, I used to ride bmx in my jeans but I much prefer tear proof short and pads now. If I do fall off (at my age) I like to have the best chance to be riding again asap. Mate fell off at the track, jeans and no pads, out for three weeks with a busted knee. He looked sweet though.
All this ‘mincers in the car park’ stuff. Live and let live. Life’s too short.