If a fasting person swallows his saliva, that does not invalidate his fast even if there is a lot of it.

There is no sin on the one who drinks or eats during the day in Ramadan by mistake and his fast is still valid.

Using suppositories during the day does not invalidate the fast. Similarly an enema does not invalidate the fast.

If the muadhdhin gives the adhan at the time when Fajr comes, then he must stop having intercourse as soon as he hears the adhan. If he does not do that, then he must make up the fast as well as offering the expiation.

1- If a man had intercourse with his wife while fasting and he was unaware of the ruling, and he thought that the kind of intercourse that is haram is the kind in which ejaculation occurs, then he does not have to do anything. 2- If he knew that intercourse is haram, but he did not know that there is expiation for that, then he has to offer the expiation.