Getting into Mumbai should not be an issue - you can easily plan to venture out and reach back to T2 airport by 12am for your 2.30 departure. There are couple of good places in and around airport or in Andheri/Bandra which would be easy for you to reach back. Try China House at Grand Hyatt in Santacruz or Stella in The Leela near Int Airport! You may push 9W kids in PNQ to check you all the way through - although I doubt if they ll put in the effort with 2 different PNRs however worth a shot as I have got it done many times!