Depends what you had done and how your service was. Usually it's $5-$17. Again, it depends what you had done...color, cut, style, highlights, etc. Hope this helps! :)
This can vary depending on where you go (e.g market, salon, supermarket...), and what you want the actual extensions to be made of (e.g human hair, animal hair, synthetic materials...) It also varies...
I generally tip 15-20%. My hair is short and requires regular cuts and colors. If it is great service I will go 25%. I travel a lot and sometimes use malls or drop in places where I generally tip...