vernonc

I flew BOM-YYZ in J a couple of weeks back. Cannot help you with the transfer in BOM as I do not know the current procedure though Jet should be able to let you know when you checkin at BLR. I do hope you have enough transit time at BOM, domestic delays are very common in India, specially as you move thru the day as most flights are coming from elsewhere and can be delayed for a variety of reasons - example fog in Delhi, Navy training exercises in GOI, etc.
Some of the domestic flight landings have been very entertaining and sometimes scary. A few of the domestic airline pilots are ex military and treat the planes like they are flying solo fighter aircraft with hard banking and very hard braking.
BOM has concierges but its hit and miss. Did not really provide any level of service. At BOM boarding can be a mess, specially if you have to take a bus to the plane. Since you are in J it probably does not matter when you board but it is a bit crazy. There were no zone boarding signs when I was there. You will need to go thru outbound immigration at BOM. There is a separate J line which is quicker for both security and immigration. It is too the very far right of the immig and security desks.
If you go landside at BOM (i.e. not via inter terminal transfer, you need to either show your ticket or boarding pass to be allowed into the terminal. There is a line to enter the terminal, a line to check in, a line for security, a line for immigration and many lines and scrums to board :-)
The checkin desk at BOM will provide a lounge pass. The lounge is not bad IMHO with bar service and food offerings and was not too crowded.
On board service is similar. I posted the menus in the International J meals thread.