Impurities

Urine splashes on toilet seat

Q: I have had rectal problems for the past couple of years and I try to keep a slight gap at the back when I sit on the toilet. However, it felt like something fell on my back and I knew for sure it could not have been urine splashing on me. Later, I tried to check if urine splashes fell on me, but I couldn't tell. When I went the third time I saw one splash fall on the seat, so I was worried if this was happening all the time but I was unaware.

My questions are:

1. Do I have to have a shower and change anything that could have come in contact with me?

2. Are all of my prayers valid?

3. Have I made anything najis from touching that part of my body?

4. This is how most people use the toilet so should I tell my family members to be careful and sit all the way back.

Touching an impure item

Q: I put a tissue around my private part. When I removed the tissue, it was damp. I had touched the damp tissue and with the same hands I touched the electrical switch and left it there for a few days. The switch is wet most of the time. I touched it when it was wet with wet hands but the switch had no trace of impurity on it and my hand did not have any trace of impurity on it. If I touched my clothes with the same hand, will the clothes become impure?