1) Try your luck with OLX. You might find one.
2) Nope. You need the SIM in the BB during activation since they do an IMEI check.
3) Not as far as I know. People on BIS have used 100-200 GB and the same 1k bill comes every month.
Yes you do get the same 3G speed as you would on postpaid. In a posh area with decent 3G signals, you could be getting around 20-25 Mbps on their 3G network.
Only Mobilink prepaid is capped at 8 Mbps, Postpaid and BIS have no speed caps.
Sent from my Nexus 6P