Yes you can , we organize these events just for you so that you can start and improve your skills.
NO. The entry is free.
All the rounds are held on hackerrank.
It improves our coding skills mainly competitive coding. If you are willing to improve your coding, then you can join this event.
You can begin with any language but the preferred languages is C/C++ and Java. These all languages are easy to learn and very fast to execute.
Yes, you can, no matter how many times you submit.