@polka6
To answer your second question... it really depends on your individual hair.
It's not so much about the "quality' of the product, as what's the gentlest developer strength that gives you what you want. The stronger the developer the more damage.
Peoples hair is vastly different e.g. some people have more layers to each hair strand than other.
Usually, a weaker strength product will work on fine hair to get into the strands & permanently deposit colour & cover grey, but a stronger developer will be needed on thicker hair.
As explained above, boxes tend to have stronger developers , so if you can instead colour your hair at home using pro products (e.g. from Sally's or hairdressing sites) that you mix yourself, that's best. As you can control the strength of developer, so its just enough, rather than too strong & doing unnecessary damage.
Very fine hair can sometimes get complete grey coverage from 5 vol developer, whereas most hair needs vol 10, at least.
If you really want to use a box, be aware they often dont state what strength developer they contain.
But L'oreal Age Perfect (& I'm talking only about their Age Perfect line, not their others) has a gentler developer... that is why it doesn't 'lift' the dark hairs much & why the coverage of grey hairs is more of a transparent blend effect than an opaque effect the same as the rest of the hair. Works v well for some people's hair, has little effect on others. Worth trying in case it works for you.
Pureplex permanent colours (except the super lightening blonding ones) also have gentler than most developer. I think its 5 vol. Its definitely less than 10. I really rate it as box colours go, but be warned they tend to come out a level or 2 darker than the box suggests.
So if you're after a mid brown, try a dark blonde first.You can always colour hair darker on the next attempt you cant 'colour' it lighter, so start light.
I've heard really excellent things about "Daniel Field water colours" - there are threads on here about how to make sure you're buying from the genuine company.
If that works as well as people say, it would be the best option for minimising damage as its super gentle.
Good luck!