I can see you are going to do well in the Aer Lingus selection with your fastidious knowledge of the Irish tax system and knowledge of Ireland in general. Perhaps sing a few ballads from the Dubliners in your interview, that will really impress them.
Taxes are low in Ireland if you happen to be Apple or Microsoft, not if you are a PAYE employee. They are amongst the highest in Europe along with a thing called USC, universal social charge which everyone has to pay as the government bailed out the failed Irish banks. I feel silly telling you all of this as you have such a good grasp of the subject.
He is from Ireland...yes, but doesn't fancy living with his parents, if you want to live in an apartment without your parents you have to pay a charge, it's called rent, perhaps you have heard of it in your country or do landlords let you live for free in return for your free tax and sound financial planning advice. Unfortunately, he is not as gifted as you and has to pay €1500 per month for a one bed in a decent area.
No, he is not bonded but all DEP's start on the same salary regardless of previous experience, cadets start on a lower salary as AL deduct training costs from their salary, again I feel silly telling you all of this as no doubt you have researched the subject in preparation for you interview and imminent move to Dublin, perhaps you spent too much time rehearsing Dubliner and Pogues ballads and forgot to check the pay and conditions of the job.
Good luck in you interview, wear a green suit with a T shirt that says "kiss me I'm Irish".