Hey,
I'm a 20 year old from Delhi who's been in Bangalore for about 4 months for an internship. My stay here has been okayish since I usually don't go out much but I've learnt a thing or two about this city.
The water will be terrible (I know this isn't what you asked for but it's so terrible that I felt like pointing it out anyway)
Autowallahs suck. Seriously. They'll charge a fuckton of money to go even short distances (some autowallahs near my society charge about 50 to 60 bucks to go somewhere 1.5 kilometers away). They're also dicks about it. So you can't argue with them because they'll hardly understand you anyway
Use cabs. Uber/Ola etc. They're much better/cheaper/convenient. Travel comfortably without paying a bomb.
Koramangala is a place with several decent restaurants and places to eat. My personal favorite is Truffles (4.7 on zomato). It's cheap as hell and the food there is the bomb. It has a lot on it's menu including massive vegetarian/non-vegetarian burgers and sausages and other stuff. It's a cafe with a lot of decent food where you should be able to satisfy your appetite in less than 500 bucks. Koramangala in general has a lot of other decent eateries and cafes too.
Other great places you should check out include Absolute barbecues which has a huge variety of non-vegetarian food (the buffet there is insane) and windmill craftworks. (Look up their locations on zomato).
To get drunk you're in luck. They don't ask for IDs unless you look incredibly young and I think the age for you to get drunk here is 18. Anyway, the beer here is really cheap in most places. I highly recommend Arbor brewery. One of the best places to get drunk imo. Also check out the Biere club and Plan B.
A colleague told me about some run-ins with drunkards/eve-teasers late at night (one happened after I dropped her off a kilometer away from her pg). So if you've got a female friend tagging along, be a bit cautious.
Can't help you out much with south indian food as I'm not that big a fan and haven't tried any places that serve it exclusively. It'll be tough to find decent north indian food here (which hasn't been violated by a myriad of south indian spices until it doesn't taste north indian at all )
I'd tell you more places if I was a bit more outgoing. Will ask other people who are and update this post later on...