There isn't really such a thing as "cycling ettiquette", only good road sense, safety awareness and courtesy.
Cyclists aren't a homogeneous group who follow a set of rules (actually there are some rules -
http://www.velominati.com/ - but they are tongue in cheek, and if you find yourself taking them seriously - the joke's on you).
So what do I personally look for in a good overtake?
- Give me plenty of space
- Take into account the road surface, don't do anything that would force me into crappy potholes at the margin of the road. Bear in mind I might have seen road surface hazards ahead that you haven't.
- Optionally give me a warning beforehand, maybe if there is not a huge amount of space or if the road surface is crappy. If there's loads of space, not necessary provided you use the space.
- Give me plenty of space
- If necessary say hello (eg if you suffer from a mental disorder that compels you to say hello to complete strangers) Don't be offended if I don't respond.
- Never, ever, ever undertake anyone. Ever. If you're in a big group then you may have to single out to get past on my right (in the UK). I choose the best line for me. I'm not moving over for you. Get over it.
- Give me plenty of space.
- Sometimes when a big group goes by the last rider tells me that they are all past (or if there's another group coming). I appreciate that. But I'm not bothered if it doesn't happen.
- Did I mention you should give me plenty of space?
Drafting is a bit of an oddity because it rarely affects me. I'm too slow to get involved in such shenanigans. However ... Never sit on a stranger's wheel. It's dangerous. If you want to draft someone, ask.
That said, earlier this year I was blatting along into a headwind in some very flat countryside. Two roadies nicely asked if they could draft. I was surprised and to be honest secretly pleased. It was a nice clear road with a decent surface so I said yes. Of course as soon as we hit a mild incline my power to weight ratio meant they had to zoom off into the distance.
Also, is this the best time to overtake? At the weekend I came up behind a group of three riders as we went round the one way system in a small town that I know well. I was going quicker than them and could have overtaken, but I sensed that they might be unsure of their navigation so I held back and planned to overtake once we were clear of the town if it was still necessary. Of course it wasn't. As soon as we were out of town they were off.