Degree

No, ITI is not a graduation degree so you have to complete your degree first for PG.

Select a college and then check whether you are eligible for distance programme.

Yes, it is a 4 years full-time degree program for UG, and it is a 2 year full-time degree program for PG.

Yes, you can do multiple degrees, if you are eligible for it.

Both courses have it's own importance and have quite different content and objective. So, go through the content and decide which will be best for you.

You have to complete class 12th or it's equivalent to pursue a degree programme.

It is better to pass your class 12th with good grades and then focus for the IIT's and Iims that will be possible then only.

Hi,
You should complete your graduation first
This is the eligibility for AFCAT
Education: Graduation (min 3 years) in any discipline with min 60% marks and have passed Maths and Physics as subject at 10+2 level B.E/ B.Tech from a recognized University with min 60% marks. Age Limit : 20 to 24 years.

Check out IGNOU website. They might have good courses.

You cannot get a Bachelor's degree after class 10th. No recognized college in India provides such a programme.