Sunnats and aadaab of wudhu

Q: During wudhu, if a person forgets to wash a limb and only remembers after washing another limb, what should he do?

Q: When I perform wudhu for salaah, I sometimes forget to put water in my nose and instead go straight to washing my face. After I wash my face, when I realize that I did not put water in my nose, then what should I do? Should I restart the entire wudhu from the beginning or should I just put water in my nose and continue?

Q: I want to know whether ghusal and wudhu can be done in a bathroom? As it is wellknown that toilet and bathroom are combined these days so is the wudhu valid?

Q: I did ghusl and wudu and prayed salah. After salah I realized I had some black residue on my eyebrows and a little on my eyelid and eye (residue for all areas mentioned was eyeliner) but this wasn't clearly visable. Even though I washed my face several times also the head area so I assumed everything was washed off. I am now concerned whether my prayer has been invalid. 

Q: I have a fungal infection in my beard, and my beard is very thick so I have been advised not to wet the skin below the beard when making wudu; beacause my beard is very thick. I know I dont have to wet the skin but can I avoid putting a handful of water and making khilal of my beard?

Q: The other day I was making ghusl, but my nose was blocked with mucus. I was told that in ghusl you should sniff water so far that you feel a stinging type of sensation. Is this correct? Because my nose was blocked, I couldn’t feel the sensation because maybe the mucus didn’t let the water touch the inner parts of the nose.

Q: Will masah of the head be valid when hair spray is used on the hair?

Q: If I already have wudhu, will I be rewarded for making another wudhu?

Q: In the wudhu, wet back side of neck is sunnah or farz?

Q: Is it mandatory to do wuzu before taking bath (after sex)?