impurity

Q: Yesterday my husband sat on a bench at the airport which had crumbs on it. I am not sure what the source of the crumbs are and I am now concerned that everywhere he sat thereafter like the car as well as the bags which came into contact with the parts of his clothes that touched the bench have now become napaak. I did check his clothes for traces of crumbs but it was hard to determine what was crumbs or just fluff and dirt and also what was the source of it as he was wearing the clothes the entire day and could have gotten the crumbs and dirt from various sources. Please let me know if I am required to wash everything that his clothes came into contact with thrice to make it paak?

Q: After I showered, I was walking out and my soaking hair touched the wall where there was napaaki and then I didn't wash it because I don't know if its napaak, is my hair napaak now?

Q: I performed Salaah not knowing that there was mazi on my clothes. It was only a few hours after performing the Salaah that I realized that my clothes has been soiled. Is that Salaah valid or do I have to repeat it?

Q: Sometimes i feel like a thick fluid is coming , colourless, occasionally even when the wife is around. Do I have to bath/ghusal?

Q: If there is dry najasat-e-ghalizah on a wall, will wiping it down once suffice? Also if clean dry clothes were placed on something that had the dry najasat-e-ghalizah on it, will they become napaak?

Q: At the time of flushing the toilet at home, a number of drops splashed out from the toilet on to the toilet floor. Having stepped on these drops, I walked in the house and then walked outside in the same slippers. The ground outside was wet in patches as it had been raining. I then accidentally stepped in a muddy puddle with the same slippers. This caused water to seep through my leather and cotton socks with some moisture getting on to my feet. Before stepping on to the Masjid carpet, I removed my slippers, both pairs of socks and stepped on to the carpet. Some moisture passed from my feet on to the carpet. I walked through the carpeted masjid and went to the Wudhu area and washed my feet. In addition I carefully left my leather socks on the carpet before proceeding to the Wudhu Khana. They were wet from having stepped in the puddle but I tried to be careful not to put the wet part of the leather socks on the Masjid carpet, but now I am having a doubt as to exercised sufficient caution in this matter, i.e. there is a distinct possibility that the wetness on the leather sock went on to the carpet. Is the Masjid carpet which I walked on paak to perform Salah on or do I have to undertake the difficult task of informing the Masjid to wash the carpet?