Here "fell on his face" is an idiom that means to bow down. Alternate translation: "he knelt and touched the ground with his face" or "he bowed down to the ground" (See: [[rc://en/ta/man/translate/figs-idiom]])
It is understood that he was asking Jesus to heal him. This can be stated clearly. Alternate translation: "please make me clean, because you are able" (See: [[rc://en/ta/man/translate/figs-explicit]])
This refers to ceremonial cleanness, but it is understood that he is unclean because of the leprosy. He is really asking Jesus to heal him of his disease. This can be stated clearly. Alternate translation: "heal me from leprosy so I will be clean" (See: [[rc://en/ta/man/translate/figs-explicit]])