ICSE

When you take admission in a university, the board through which you cleared your 10+2 does not matter. The difference between the two boards is in the difficulty level. If you choose CBSE, the difficulty level is much lesser than that of ICSE. So choose the board on the basis of the pressure you are willing to take.

CBSE is a bit better because there curriculum is very simple.

Hii Aslam, From class 11th start preparing for JEE entrance examination.

CBSE Syllabus is much better in theoretical knowledge, but ICSE syllabus has the upper hand when it comes to practical knowledge. Level of Ease, CBSE Syllabus is much easier, well structured, and compact than ICSE Syllabus. ICSE Syllabus is tougher when compared to CBSE because of the detailed study of all the subjects of ICSE Board. But ICSE Syllabus provides more practical knowledge and it aims to build analytical skills in students.

Choose the board which is nearby you. If you have both, then go with ICSE. If you choose CBSE, join him in coaching class. It will make him more competitive.

CBSE will be suitable. Because he could adapt to ICSE now. CBSE will be a good choice and ask him to prepare for entrance examination.

Both are best in their standards. If you are an ICSE student, pursue in that. Because it makes you more competitive. If you want, you can move CBSE, it will be little easier compared to ICSE. But if you are CBSE Student, don't move to ICSE. It will be little difficult to adapt.

Yes. There is no problem in taking the same.

You are eligible. You can teach but you should clear CTET exam.