... to pull the foreskin back like that. There is no reason whatsoever that you need
Even during intercourse, if the foreskin is pulled back hard, it indicates that there is insufficient lubrication (with vaginal transudate from the woman - and "pre-come" from the fellow if not wearing a condom, and a condom prevents the foreskin from being pulled back excessively in any case) and if this is not corrected, it will be quite unpleasant for the woman as well
You note the design of the meatus such that it angles up slightly (unless
pulled). This is pretty convenient for gymnastic peeing and compensates for the fact that the urethra actually travels along the underneath
of the penis as you would have observed. Presumably, it is also "aimed" strategically to lodge semen optimally at the cervical opening.
I won't answer "how long" - it clearly depends ...