1. ive read something about wheel openings
Not sure what you mean here...
2. on different years does the pheonix face different directions?
The birds head faces opposite ways dependng on the year.
'73-'78 - faces to the left ...'79-'81 faces the right side of the car (except for Turbo models which face left).
somebody mentioned that people like to watch a certain years' tailights for whatever reason... do they dance or something?
No dancing lights lol The only difference I can think of is that '81 only has the bird on the gas door. '74-'78 are the same lights and '79-'81 are the same with the exception of the '81 I mentioned.
4. any interior differences?
The main difference in interiors between those years would be if the interior is standard or deluxe. '78-'81 also offered different seats and door panels vs the '77.