Proposal for a pinned Neopixel basics and help thread

Thought it might be more efficient to have a general thread that answers a lot of the questions we've seen popping up RE: pixels lately.
Good chance to give an overview and scrawl any notes we all might have gathered up.

I've started writing one up that could be the basis of a thread, and it includes what I've learnt and picked up over the last few months.
Please do feel free to add more stuff if you're fairly sure its accurate.

https://1drv.ms/w/s!AjPBRKh42r09jFj8Y7PJ3ZbDekFs

Good start.