Government Polytechnic Pune

Yes, you will get admission in GPP.

You can't get admission in direct second year if you don't have Diploma. So, if you have Diploma you can fill for counseling otherwise you have to start from first year itself.
Good luck.

Yes, there are some chances to get a government college for Diploma. However, your percentage is very low and they provide merit based admission.

No, you can't give this exam after class 10th. You have to complete your graduation for this exam.
Good luck.

If you get 90% in class 10th, or more than that, yes you can definitely get admission in Government Polytechnic College-Pune.

There is no way you can get Admission directly into second year computer or electrical engineering after passing 12th standard. The admission directly into 2nd year is only permissible for diploma students through lateral entry entrance examination. So, you can only get admission into first year through JEE or any other state level examination.
All the best.

Here you find out all the eligibility criteria to get admission in this college
https://www.shiksha.com/college/government-polytechnic-pune-shivaji-nagar-4235/admission

Yes, you will get admission for any of the branches with 78.5%. For electrical branch, it is a little bit difficult, but for that also, 60% chances are there.