Impurity on body, clothes or place of Salaah

Q: I burst a pimple on my thigh to remove its pus, and just rubbed the pus with my fingers, then I wore my undergarment and pants without cleaning the pus and/or blood that got stuck on my thigh after rubbing the pimple, nor did I clean my hands. Now, some amount of pus will stick to my clothes.

Is it allowed or okay to pray in those clothes and without cleaning it (pus) with water on my thigh and fingers or without taking a shower? I read on some websites that a small amount of pus or blood is okay and it will not break the wudoo, but my question is, will the clothes become najis after such activity or shall I take a shower to make myself clean before I pray, or at-least clean only where pus or blood got stuck? 

Q: If small baby urinates on my shirt or pants, will it be permissible for me to perform salaah with such clothing?

Q: If a person is praying at home on a clean floor, should he still spread out a prayer mat to pray on, or would this be unnecessary since the floor is clean? What would be the best for him to do in this situation?

Q:

1. If I place a clean musalla on an impure carpet can I pray on that musalla?

2. Also, if I make wudhu and then stand with my wet feet on the musalla that is on the impure carpet will the musalla become impure since the water penetrates the musalla and goes to the carpet or will it be pure. Because I heard a masala that if you wrap a wet impure cloth inside another cloth the other cloth won't become impure.

Q: Is it permissible to pray wearing shoes? Because I've read a hadith that it is permissible so I just wanted to clarify it.

Q: My question is if clothes becomes najis after the salaah and it was clean during the salaah will the salaah have to be repeated?

Q: I sometimes find after performing Salaah, a little dirt under my nails. Most often my nails are short. What will be the condition of my Salaah? Is it valid?

Q: Thew new £5 UK note is made of plastic and contains animal fat. Can one pray salaah with this note in their pocket?

Q:

1. Is it permissible to use the new five pound notes as they contain animal ingredients?

2. When praying Salah by having the £5 notes in the pocket will the Salaah be valid?

Q: Recently I performed two Salaahs at a jamaat khana. However the next day I realised my underwear was soiled. What should I do?