There are always packages available but your best and most economical bet is to book B&B and then ask for a Voucher for a meal in the restaurant at reception when you check in. There is a 3 course Table D'Hote menu available and it is excellent value and they will even deal with special dietary requests. Highly recommend this option.
I got lucky and booked a Dinner, Bed & Breakfast once during a Flash sale plus 25% off at the start of the year. If your signed up to H Honours scheme you get emails letting you know if any sale's are on.
to my knowledge they don't
Some Hiltons offer dinner bed and breakfast packages, but not sure if Glasgow do. They will certainly do bed and breakfast rates.
Get an answer from Hilton Glasgow staff and past guests.