Doesn't sound very normal to me, but I could be totally wrong.
I have never seen anyone being requested for proof of status. Since US and Canada share information, I'm not sure if they came across something for them to request this. While long processing times are normal in some cases, if you see anything above norms of your peer group from same visa office, then you might consider checking in on what's going on. You should apply for gcms notes and see what is going on with your application.
Transcripts request is also not normal. Degree certificate is the only mandatory thing for education, and it is the part of R10 check.. So if that's missing , then they'd have rejected your application as incomplete, and wouldn't be requesting it from you. Pay stubs and W2 are not mandatory documents too and I have feeling that they're requesting it to check your legal status rather than employment.
Also, what is your country of residence? They transfer applications to local visa office specifically if they need some background information on the local things like verifying employment or other background in that region. If you reside in London and if they've transferred it to US visa office, they are trying to more on your US stay.
Have you ever been out of status or overstayed because of things beyond your control by any chance? Or been out of work while on H1b? Do you have i94 for all of the time that you stayed?