You need to first file representation on this ground and letter go for writ petition in the same

You should have obtained order from court that you are entitle to national appointment than your seniority would have count from first appointment. 

Can file review petition in court to request the court to grant notional benefit than only you can claim benefit of seniority with other batch mates.

Dear Sir,

You can surely file a writ in this regard.

Kindly provide the information of the terms and conditions of old service and the new

Yes you will get 2 years benefits, go for writ petition 

You say that you have been appointed into the service after the judgment by a court of law in this regard. 

You can go through the judgment for knowing about employment status,  seniority protection etc.   

Without knowing the contents of the judgment,  any opinion given in this regard may be misguidance. 

Yes you are fully eligible for promotion along with all your batchmates. 

Yes,Definitely you may do that on the principle of parity with your colleagues. 

Your promotion, job,ACR,leave and increment are the subject matter during pendency of Court case and it doesn't affect your service because of litigation due to fault of management to process your recruitment withon time fram and appoint you as per rules.

You can't be held responsible for the wrong reasons and action of the management through regular court proceedings against you upon unfair and unconstitutional charges against you for your lawful appointment. 

You may file writ of Mandamus   before High Court seeking direction against the management for the relief of  your grievances which were unequivocally caused to you unfairly, unethically and illegally.

1. Yes if you will get all the benefits of seniority if you win the case.

2. You can file writ petition to claim your benefits if denied by department.

Promotion from retrospective date shall be granted in case a delay. you may file writ petition. 

Dear Sir/Madam,

You may very well file the writ petition and avail all the benefits entitled to you.

1. As per the information mentioned in the present query, makes it clear that you have somewhere rightly mentioned about the benefit of your regular service at par equal with others or not.
2. I would like to apprise you that as your seniority will not compromised, so the regular service can also not be compromised at all as both are consequential reliefs to each other.
3. Yes, you have an only best option to approach the Hon’ble Delhi High Court under Writ Jurisdiction as per Article 226 of our Constitution of India with all the documents with you.