Thanks Robert.

So I was wrong about Arbat being in the accusative because of being in apposition to another noun... I only got it 'right' by chance as the declension is the same as the nominative!

And this is because of the exceptional case of 'street' being a generic noun, is that correct?

If it's not too much trouble, how will I know which street names decline like adjectives? Are they ones named for (after) other places and people?