JoSAA

Within 3-4 days or hardly 5 days. You will get information regarding it on provisional seat allotment letter.

After getting college in 7th round then also you can go for special / CSAB rounds. If you don't get any seat then your last seat will be there for you.

You can take part in CSAB round, but if you get seat in NIT and want to get refund from IIT then it may create problem, you may lose your money. So, take decision nicely.

If you have done reporting in round 1, then you only need to go when you have to freeze your seat or have to slide your choice. For freezing, you just need provisional seat allotment letter as rest are verified already but carry all the documents. You need to have documents if you are going for first time at reporting center, like category certificate, class 10 & 12 certificate, 3-4 photos just same as uploaded during JEE Mains form fill-up, medical certificate, seat acceptance fee receipt, Aadhar Card, provisional seat allotment letter, undertaking paper, locked choice page. Also carry 1 copy of each along with original documents.

Yes, it may create problem in the refund of seat payment amount. Also, now you aren't eligible for JOSAA and CSAB.

Yes, after round 7 there will be a spot round. It takes place normally after 3 - 4 days of JoSAA last round.

You may get chance to change the preference order of your choice fill-up and also, to delete some choices but you can't add new choices.

You have to pay the seat acceptance fee amount only. When you report in college for admission then you have to pay the rest amount of the semester fee.