There is nothing wrong with a fasting person diving into water or swimming in it because that is not among the things that break the fast.

We do not know of any scholar who says that a bee sting or scorpion sting is one of the things that invalidate the fast.

Popping pimples that appear on the face does not break your fast and you do not have to make up that day later on.

There is nothing wrong with a fasting person if s/he gargles their mouth with water, or with water and salt, especially if there is a need to do that.

There is nothing wrong with tasting food while fasting and it does not affect the fast so long as none of the food enters the throat of the fasting person. This applies equally to coffee and other things.

It is permissible for a man to sleep beside his wife in Ramadan. In fact, it is permissible for a man to be intimate with his wife when he is fasting, so long as no intercourse or ejaculation takes place.