Various masaail of Salaah

Q: If one suffers from knee pain, can one pray on prayer mats that are softer and thicker at the feet and knees end than the sajdah end, such that the sajdah area becomes lower than the feet and knees?

Q: Can sajdah shukr be done immediately and openly.

Q: Can I offer namaaz while wearing glasses?

Q:

1. Can one pray in front of a mirror?

2. Can one pray in a manner that a mirror is next to him and he is not facing it?

Q: I was sitting after performing salaah when I noticed that there is a black, sticky substance on my foot through which water could not pass. It was the size of a whole round fingernail, and I had not seen it before.

Then, my brother told me that he saw it since 3 or 4 days on my foot. I had also led jamaat during these days. Will I have to repeat all the salaah that I had offered on these days? Will those who followed me in jamaat also have to repeat their salaah?

Q: If I use a miswaak before performing salaah at home alone, will I still get the reward of 70 times more as if I were to perform the salaah in the musjid?

Q:

1. Is there any hadith that states that the reward for praying salah applying itr (fragrance) is 70 times more than offering salah without applying itr?

2. The same reward I have heard for offering salah wearing an عمامة (turban) for men, is it stated in any hadith?

3. Is the above mentioned reward given for a person praying salah after doing Miswaak as well?

Q: I find it hard to motivate myself to do what is right for me and my religion.

Example, I wake up three consecutive days and pray tahajjud. After that I am unable to even wake up. The same applies to the five times Salaah and seeking knowledge. I become lazy and end up forfeiting all these acts of virtues for a long period of time. When I do end up starting again, I do it for another three days and leave it again. I wish to be consistent in Allah's obedience and worship.

Q: When I start offering salaah, I start yawning frequently. How can I get rid of it?