The more natural way to say this first sentence is, "One day last year." In the second question, the use of "only" can get complicated. Your first sentence, "In this work, he played the character of Christy Brown, a cerebral-palsy-stricken painter who can move only his left foot." the implication is that this person can move his left foot and no other body part. However, in the second sentence, "In this work, he played the character of Christy Brown, a cerebral-palsy-stricken painter who can only move his left foot." the implication can also be that he can move his left foot but cannot do anything else with it, for example, he cannot lift his left foot. So there is a slight nuance of different meaning when you put the word "only" before or after the verb.