Teacher

Yes, it is fine.
Start with B.Ed. program after 12th and then go for M.Ed. or do Bachelor's and Master's in your specialized field.

Not recommended, please get a reference letter from 9th and 10th counselors or teachers only, someone who is currently evaluating you and knows your skills well enough. Your 8th grade teacher may send in an additional report.

A good score in the NET exam always helps. You can get a job by applying when the government universities release advertisement for recruiting professors, they conduct an exam and if you pass it then you are almost good to go. Just an interview follows, usually. Also, in the meantime, you can start teaching at a private or deemed university. Experience always counts positively.
There is also a provision of teaching along with pursuing Ph.D. Look into that too.

He/she has to complete his Masters and then he can opt for UGC NET or M.Phil.

You have to clear or complete your Bachelors degree with 50% or more marks with B.Ed. courses. Masters degree is preferable.

Yes, you can get it. Meanwhile, it is recommended that you develop an experience of at least 3 years so that you can qualify for entry position into IIM's teaching faculty.

You can do graduation in relevant subjects and for deep knowledge and better position, you can go for Master's degree.

Yes, B.Ed is accepted as a qualification for teacher placement across the country.