Engineering

Hello Manikandan,
From this year onwards, TN govt. will not conduct any entrance exam and admissions will be based on marks obtained in 12th. Though one needs to apply online to be included in the process. I am attaching a link that will give you all the required information.
http://www.tnea.in.net/

No, you cannot get admission in PEC without JEE Mains.

Dear,
You are to appear in state level JEE for admission in polytechnic Diploma Engineering. The concerned council gives a wide circulation through all leading newspapers. You are to follow them. You may also visit JEE council's official website.

TANCET 2018 Application Form is expected to release soon. You can apply for TANCET at its official website, i.e. Annauniv.edu.

There is no home state quota for DAIICT. The seats in DAIICT are allocated as follows for the B.Tech course:
Out of the 300 seats, 150 seats are allocated through the state counselling process called ACPC and rest through All India Quota and NRI quota (~ 5%) for which a rank list is prepared based on

You can take admission in HBTU on the basis of your JEE Mains rank and the university will conduct their own counseling on the basis of your JEE Mains rank because HBTU is not a part of UPTU since 2016.