Double void (urination) may be due to many reasons. Evaluation by a urologist is advisable.

Yes. Once your bladder is full, the kidneys can no longer empty. Once you empty the bladder, then the kidneys diuresis the rest of the urine that was in the kidneys and then comes down into the bladder, making you go to the bathroom again.

Dr. Niko Lailas

May not be any physical problem and likely can improve with kegel exercise.

No going to the bathroom more often than every two hours is abnormal. This is most commonly do to overactive bladder, but can also be caused by more serious things. Need to have a urinalysis. Start by reducing caffeine intake, and de-constipation if not having daily bowel movements.

No. You need to see a urologist. Your problem may be as simple as urethral stenosis. Can easily be corrected.