I can add to the list of things Mumbai airport should do to help passengers. The first priority is to have a website with the telephone numbers of all airlines operating from there and a complete, schedule of all arrivals and departures which is constantly updated.
I also see that the parking charges have been hiked to Rs 50/-? Why this hike when no additional facilities have been offered and inflation is not running at 50% in India. This just goes straight to the parking lot operators pocket.
Finally there should be a small underground rail or overground monorail connecting the two terminals. This should be a free service available to bonafide passengers only. In the interim, they can build a fenced off corridor and allow airline buses to travel along the airport side.