JEE Advanced

Hello Jagdish,
Once you got yourself registered for JoSSA then you need not register for it round wise, if you don't get any seat in the first round then simply wait you may get any seat in 3-4-5-6 rounds.

Yes, ofcourse if you want to get admission in that college, you must have a good score in JEE Mains. JEE Advanced score is not required if your Mains score is good.

Hello Antarip,
Well, both are reputed coachings of India so you can take distance material from any of them, however considering more accurate and straight towards JEE Mains and advanced questions prefer resonance materials.

I will tell you about how much rank you need to score to get admission in aeronautical engineering, so the rank must be around 4000 (general) in JEE Advanced and minimum 75% in 12th board exams to be eligible for JOSAA counselling.

Hello Rohan,
As per your rank your chances are nil to get any IITs if you belong to general category,however check here to be more clear:
https://www.resonance.ac.in/reso/news/jee-advanced-branch-allotment.aspx

Hello Raushan,
As per your rank, your chances are high to get any campuses of IISER, however, check here to know more.
https://www.resonance.ac.in/reso/news/jee-advanced-branch-allotment.aspx

Hello Peesa,
Seats in IIST are allotted strictly as per your rank. If they have your desired Specialisation at the time of Admission then you must give your choice for this. But possibly it could be optional subject later on then you have to choose main branch first.

What is your category?

First and the foremost advice would be to learn all the basics only and only through NCERT. Now, you must have joined any coaching, so just solve the material and never go for the theory part. Follow your notes and have a short note or cheat sheet of each and every chapter. October to December should be devoted just to test series.
Take them very seriously.