Summoning Etiquette

So, I always felt like a newb when I needed to summon someone to help me with a boss.

And then I started laying down my summoning sign and realized, people aren't looking down on me when I summon them for boss fights. They're psyched. It's awesome.

And when you're hanging around an area farming and waiting for someone to summon you, it sucks when it doesn't happen.

Still have some questions on etiquette though.
So, now I summon pretty much any time I'm at a boss fight so people can get their rewards. Its fun.

But is it a good idea to summon two people so they can both get the rewards or is that annoying?

The other day I summoned a guy to Dancer, and he was using poison mist to kill Dancer. So, I guess I'm supposed to just stay out of the way? That seemed a little rude to me. I can see doing it on Medir but on Dancer?

Any tips on good etiquette for summoning and being summoned appreciated.