Twenty years ago I was in precisely your position, with precisely the same questions, and at precisely the same market levels near all time highs. I asked an experienced options broker if it would be a good idea for me to sell puts. No, he replied. Because shit happens.
I didn't listen then, and shit happened, as in time it always will.
It has also been my experience that threads like this, with traders advising a newbie to engage in selling puts, is a good sign that we are at or near a market top.
Good luck.