a-- it's OK in context if the street has been mentioned in the conversation; if it has not, of course, then more information is needed. The sentence itself is fine. If I say 'I got an A+', the sentence is fine, but the listener is still going to ask 'In which class?', of course.
b-- The same, yes.
c-- Yes. Or 'follow the curve to the left' or 'bear left'.