Guidelines for playing draws on the flop?

[Marlow]

When I first started reading this forum a few months ago, I was suprised that people advocated playing fast with draws on the flop. After reading and thinking about it for a while, I have some vague ideas about what is optimal and what isn't, but I don't feel as though I have a solid handle on it.

Here's what I know for sure:

<ul type="square">[*]A flush or str8 draw is about 2:1 against hitting with two cards to come. With around 11 outs, it's around 1.5:1 against. With 13 outs, it's even money to draw to a hand you know will win against a made hand. [*]I know that it's good to be the aggressor when the odds are there, as to gain fold equity.[/list]
But then there's the stuff I'm unsure of, such as:

<ul type="square">[*]How to vary my play depending on the depth of my opponent's stack (assuming I always cover). [*]How to play against two or more opponents. [*]How much to bet. Is it Ok to overbet the pot in certain situations? [*]Should I ever put in a bet or raise when the board is paired?[*]What do I look out for when I've got the non-nut draw?[/list]
I've got a few specific examples in mind, but I wanted to paint this in broad strokes first.

Thanks for your help,
Marlow