Switching wife's visa from PSW to Tier-2 dependent

[revv]

Hi Folks,

Apologies if this has been asked before, but I haven't been able to find the exact answer to my questions.

I am working in UK in a Tier-2 general visa, and my wife currently lives with me here in UK on a T1 PSW which runs out in January. I have been told that she cannot switch in the country to be my dependent and we have to do it from outside UK (correct me if I am wrong here plz). I was wondering if you guys could help with the following:

1) She has an Iranian passport, and with the closure of the British embassy in Tehran it means we have to go to UAE, and stay there until her visa is processed. On average how long does it take for a dependent visa to get processed? (she has both UK+shengen visas in her passport)

2) What kind of supporting document does she need from me? I know bank details, statements etc have to be provided for maintenance funds, but I dont know what documents "I" have to provide apart from marriage certificate +official translation. Do I need to provide my own Biometric card or passport?

3) I looked at the application form and it asks for Reference numbers for her previous visa and myself. Are these reference numbers the same as the Biometric card numbers, or is there any other ref. number I ahve to find out about?

4) And finally, do we "have to" wait for her current PSW visa to run out before applying, or can she switch before her current visa runs out?

Thank you in advance, and sorry for asking any too obvious questions.

Cheers,
Revv