Can I travel to India while on job search in Ireland

Hey

Facts:
1. I am Indian

2. Started working on 22 August, 2016 in Dublin with Critical Skills Work permit valid from 22 August, 2016.
2.a. Renewed GNIB and Irish re-entry visa stamp on 31st July, 2017.

3. Stopped working in Dublin on 28th October, 2017 and moved to London with for a new employer in london with Tier 2 general visa sponsorship, while still holding GNIB card and Irish re-entry visa stamp valid till 1 August, 2018. I did not return the Critical Skills Work permit (I am still not sure I had to!)

4. Stopped working on 11 January , 2018 for the new employer in London. Employer stopped Tier 2general sponsorship the same day.

5. On 1st Feb, 2018 I went to Dublin to give interview for a job in Dublin. Immigration officer at the airport said that I shall return my GNIB as it can create problems if I get the job and he said he marked this in the database.
6 . On 2nd Feb, 2018 I got the job offer in Dublin. I still hold the GNIB and Irish re-entry visa valid till 1 August, 2018
7. The new employer is going to apply for a new critical skill work permit on Monday 4th Feb, 2018.

Questions:
1. Can I travel to India and come back to Ireland with the existing 'Irish re-entry visa valid till 1 August, 2018'?
2. Shall I return the GNIB 'which is still valid till 1 August, 2018' ? Can it really create problems for getting a new 'critical skill work permit'