Dye and Mehndi

Q: I am a twenty years old. Since January I have a disease. Now I am recovering. My question is that this disease has caused my hair to turn white before age. I know that it is haraam to pluck white hair and also that one falls in Allah's eyes by doing such deeds. But I have also heard that young muslims can even dye their hair black if they wish. I want to ask that is it permissible to pluck such white hair that are growing before age and are a result of a temporary disease?

Q: I have heard that applying mehndi (hena) before eid (on the night of eid) is sunnah and will you get reward for applying it on hands and feet. Is this true according to Islam? If someone don't apply for eid or before eid, are they committing a sin? Will they get punished for it?

Q: Can a male dye his hair red or blue or any other colour besides black?

Q: Is is permissible for a man to have  mehndi on his hands. Please give reference from Quran and Ahaadith.

Q: I want to know all the rules for colouring the beard. Can I make it red or black?

Q: Is it permissible for a Muslim lady to tint her hair for her husband only?

Q: Can women apply henna on their hair?

Q: Can women dye their hair?

Q:

1. What is the Shar'ee ruling regarding hair dye? Is it permissible to use?

2. What colours of dye should one use and which colours should one avoid using?

3. Is there any difference in the ruling between men and women?

4. Is it permissible to use hair dye which is non-porous and prevents the water from touching the hair? If one used such dye, will one's wudhu and ghusal be complete?

5. I heard that applying mehndi is a Sunnah. Can a person dye his beard or hair with mehndi and will one receive the reward of the Sunnah if one applies it?

Q: I would like ask when getting ones hair professionally dyed, bleach (ammonia) is normally used to aid in transitioning from dark to light or vice verse. I have heard that ammonia forms a layer over the hair but am unsure whether this is true as Islamicaly permanent dyes are permissible. Please let me know whether getting ones hair dyed professionally is allowed particularly when it's to cover grey hair as a means of adornment for the husband.