Night fall is a problem of early ejaculation, with suitable medication and instructions it can be completely cured. Regarding you next doubt, it appears to be a problem of Phemosis, a condition where the foreskin covering the penis head is tight. There is difficulty in retracting the foreskin back easily. The head remains coverd even when erect. For this you must once show yourself to a general surgeon. He may conduct a proper examination and assess the severity depending upon which the management can be decided.

Semen production goes on in the testis for 24 hours and gets stored in seminal vesicles. Now imagine seminal vesicles as a water tank. 24 hours production at some time, will make tank full. Its storage capacity runs out. Now overflowing mechanisms take place like night falls and seminal discharge in urine. To avoid this u need to have sex or masturbate regularly.