Impurities on clothing and furniture

Impurity on one's shoes

Q: It was raining outside, the sole of my shoes were wet, they touched the top part of my other shoe. The shoes are made of absorbent cotton material. I understand that doubt cannot uplift certainty. But I know that I must have stepped on some kind of najis some where so I think the top part of my shoe became impure, but even if I did there was no trace of it. Also before I stepped on my other shoe I walked for a bit on wet ground, would that have cleaned up the sole of my shoe? I suffer from waswasas as well.

Wears slippers with pigskin soles

Q: Someone wears slippers with pigskin soles. If he now takes off the slippers and walks on a carpet, does the carpet becomes impure? The person was wearing socks with slippers that were not wet, but as you know the socks get kind of humid/ from feet heat when wearing/walking. Does such dampness (without actual wetness) transfer the impurity or must it be real wet?

Urine problem

Q: I m suffering from an illness of urinary dribbling (urine drops coming out). I want to ask you that if I am out of my house and after urine I feel urine drops, can I wash the affected area of cloth with water for Namaz or I should have to change clothes for Namaz?