They don’t offer dinner. They said that as train starts at 9.35 they will not provide dinner. However from morning they’re going to give everything
Yes, you will be offered food for free in the Nizzamuddin Eruklam Express (12284) as you are already charged in ticket.
For evidence see the screenshot below which I took in the IRCTC website while booking ticket for the same train.
To answer your second question the train usually reaches Manglore on time.
Credit:stackoverflow.com‘