MCA

Yes, you can do MCA after B.Sc course. Those students who have done class 12th or graduation with mathematics subject then they are eligible to apply. The admission in MCA course is through the entrance exam, which is conducted at the national and state level every year.
If you have good command on the programming language then you should move on this side otherwise not.

Following are the non software fields with good scope in the future -
1. Network Admin
2. System Admin
3. Database Admin
4. Technical support for a product
Point 4 must be avoided if possible. Rest are good jobs. But its hard to grow if you hate or don't know programming.

LNCT is one of the best private engineering colleges in Bhopal for the same.

Prefer MCA for being safe and learn cloud computing and mobile application development as your interest. Diploma can cause you pain in terms of the Degree asking requirements in India.

JNU does not offer MCA by distance learning. You may evaluate IGNOU for same.

MCA is best for you because you already have an idea about the study pattern, but you can choose M.Tech as well, it makes you specialist in the field. You are also eligible for MBA.

Yes, you can work for both the fields.

There are a lot of jobs available for teaching in schools, colleges, institutions, universities, etc.