Hair and Nails

Q: I've lost 90% of my hair. Can I use hair extensions in this case? 

Q: When dying the beard I know black it not permissible, but can we mix black and brown to get the beard as dark as possible?

Q: Is it permissible to use hair dyes which contain keratin?

Q: What is the maximum hair length a woman can keep? Can a woman keep hair length till her knees?

Q: Please explain which portion of the hand is it sunnah to apply mendhi to?

Q: When growing long hair, is it correct to trim the hair that exceeds the hairline, such as:

1. The hair around the ears, which covers the ears when the hair is combed downwards and curls up when the hair is combed backwards, is it correct to trim this hair by using a scissors or a machine around the ear?

2. The hair which exceeds the hairline at the back of the head, is it correct to trim this hair to the level of the hairline at the back?

3. The hair that exceeds the hairline on the sides of the back of the head, is it correct to pull these hairs to one side with a comb, and trim off whatever exceeds the hairline?

4. The hair of the sideburns from the top of the ear till the middle of the ear, if the sideburns become too long and look untidy?

Q: Is it haraam to trim the beard, be it with scissors or any other machine?

Q: I'm aware that a woman cannot tie her hair high on her head which would resemble a camel's hump.

I would like to know if she is allowed to wear a high ponytail or bun, which sits at the top of her head, at home only?

Q: Is it permissible to dye ones hair? I mean to highlights ones hair any colour beside black?

Q: Can a man cut long hairs of eye brows?