Can we have a hairdresser AMA?

[PrincessBuggerPants]

I'll start with my questions:

Which is a better choice for doing my hair dye tinted roots? Henna or box dye?

How bad an idea is it to give myself an undercut on a short, layered bob?

Thanks thisenglishlife, I've just washed my hair so going to try this now.
It's worked on all the super straight hair I've tried it on so far.
My hair is the same, it doesn't curl with heat, it just gets bent. You have to keep trying different ways with the plait and bun, until you find the method that works for your hair.

The method for my own hair is - dry hair, two or three section plait and then put into a bun. I leave for a few hours or overnight. Then when you wear you hair down, it is all wavy. It looks shinier too, as there is more light hitting your hair at different angles.

Another question please.
Thanks for the recommendation regarding scissors
Are offset scissors suitable I have lots of mid to long length slightly wavy hair.