Is it necessary to take coachings if I want a rank below 5k in Jee Mains? If not then what are the preparations required to get that rank?

Coaching is not at all necessary to get admission in IIT's or NIT'S. I have cleared advanced and am currently in one of the oldest IIT's just by myself. Hard work and dedication is all you need. I won't tell you how many hours a day you should study cause that's totally on you decide. You are the one who knows your caliber. Smart study is important. Solve as many previous year questions as you can. Try to keep away from distractions at all times and above all, enjoy these subjects. Studying a subject with hatred in your heart won't get you anywhere. Revise as much as you can and don't lose hopes.

Just follow Ncert book line by line for chemistry....for physics- ncert and hc verma and for maths-follow ncert first then rd sharma,arihant.......just be consistent with your studies.....only 5 hours a day would be sufficient till 11th class then 6 hours regular study in 12th class....practice last year jee paper (it's easily available online free).....that's it...and be motivated all the time.......best of luck