If you want to avoid crappy food for dinner/lunch inside train, get in Hotel Swathi outside(opposite) to Platform no.1 side. Reasonable price and you get good food.
like most Indian railway stations, the Secunderabad station stinks to the high heavens. entrance 2 however, is a heck of a lot better. cleaner, more organized and the dogs are friendlier. :-)
There are no ATM's available inside the station. You can find ATM outside opp to the station. Unless you have train on PF1 don't wait on PF1, it is always crowded.
There is a MMTS ticket counter on platform 7 but the trains 🚊 from Falaknama to Lingampally may not come on to this platform. So pay attention to the announcements.