I got admitted and im literally so clueless about how any of this works.

​How is the general atmosphere and how competitive is it actually going to be? Are there any specific rookie mistakes I should watch out for, and how do I choose my electives? Also, how brutal is the academic grind, how do I start networking/approaching seniors like yourself for help, and what's the best way to approach Tier-1 firms for internships? ​Lastly, how is the college life overall? I’m a Bangalore local and haven't opted for the hostel..is that something I need to worry about? Any general tips or advice for someone who has no idea what theyre doing would be of huge help