I hope u are all good and kicking

One of my mate and her wife have applied for my post study visa and asked me the following qs which i thought it will be nice if u guys can assist me with it
1.the documents we sent were:
Passport, Police registration, 110 days bank statement exceeding the £800 limit, Letter from their uni confirming that they will get their award and ..( as stated in UKBA website whereby the letter is used as a replacement for the qulification degree paper), 2 photos with names written on the back
Is there anything they have missed? should have they sent a marrige certificate ? ( they have made a seperate application each ann no one is dependent of the other so they haven't sent the marriage certificate)
2.they need their visa asap but have been told that they need to do a biometric test which is done after the home office recives the apps and then contact them to do it. Can someone please explain about this procedure and how long will it take.
from ur point of view, how long would the overall app processing time takes( the UKBA says 4 weeks but want to get opinion from other peoples and preferabaly someone who has applied before)
My self app didn't take that long