Massallah pertaining to discharge

Assalam-u-aliakum Muftisap,
1)After I urinate ther is a clear liquid discharge that comes out. What discharge is this?
2)After making wudhu if there is a discharge is the wudhu broken?
3)If one”s satar is exposed during making of wudhu , does this nullify the wudhu?
4)Is there any specific medication for waek erection/pre-mature ejaculation?
Jazakallah