I think it comes with playing and listening. jtsang, your method is OK. I guess if you keep at it, you'll get there. After you know the first note to a song, do the reverse - think of that song and sing the first note. Then play and see if you are correct.
As for emotions, it is also true. A flat and D flat give me particular melancholic feeling, as opposed to F sharp, E and B, for example. But it is not something easily explained - I can't. I think better not stick with emotional feelings but proper ear training.
Before I found out the existence of perfect pitch, I used to have 2 pieces of music in my head - one starts with A and one starts with C followed by F. I can sing these notes accurately to the pitch. Then I applied interval theory to find the other notes I hear. It was only later I realised I didn't have to do that. Then, came the notes of ambulance sirens and school bells ...