I believe it does but normally these are fitted with the diversity aerial built-in to the rear screen to ensure good radio reception.
The roof-mounted shark-fin, the roof-mounted bee sting, and the rear screen diversity aerials - generally one or the other is activated, not both.
No, that is not correct in my experience.
It will depend on the type of factory fitted equipment.
The cars with RCD-300 and no phone prep will only have the one bee sting connected (and a single aerial plug) at the head unit side of things.
If you had the RCD-500, MF2 / RNS Nav then you would have the diversty aerial connected (and a double aerial connection at the head unit end).
You are sort of correct, and I was sort of wrong.
Basically, the RCD300 has just one radio tuner, and so is not able to utilise the two 'inputs' of the rear screen diversity aerial.
However, the RCD500 and RNS-MFD have two separate internal radio tuners (the giveaway is the ability to be able to record and store traffic announcements). These definately need the dual input of the diversity rear screen aerial - however, they may also be supplemented (or) not by a roof aerial - dependent on other radio receiving equipment (car fone, sat nav). Generally, the RCD500 with no other kit will not have a roof aerial, but a roof aerial (but who knows what type - shark fin, or shark fin with stubby bee sting) will always be fitted with either sat nav, or fone prep, or both.
Other difference will be the early 05 plates what don't have a roof aerial at all.
Correct.