Various masaail of Salaah

Q: If a currency bill falls out of my pocket on the praying rug with an animate picture visible, would it affect my Salah?

Q: I have been gifted a memory foam musallah. Is prayer permissible on this mat?

Q: Zaid was working outside on the roof of a attic, when it was Salah time instead of coming down from the rooftop, he prayed Salah on top of the roof of the attic with his shoes on, is the Salah valid?

Q: Zaid was working on the roof of an attic. When it was Salah time, instead of coming down from the rooftop, he prayed Salah on top of the roof of the attic. Is the Salah valid? 

Q: Is it correct to say that salaah was the first command (or possibly one of the first commands?) to be given to every single messenger?

Q: Is it permissible to do nafl ruku out of salaah like we sometimes do nafl sajdah?

Q: Is it alright to pray behind someone sitting in the mosque? And if someone is praying right behind me, can I move or get up from from that place?

Q: I don't have a right hand index finger the one we raise in Salaah. Does this mean anything in Islam?

Q: If any person shaves his beard, will that have any effect on his Salaah? Will his salaah be valid?

Q: Ruling on a person taking drugs, when can he read or touch the Quraan and or read namaaz?