Either IT Search or your end employer will provide you with a formal letter of offer or a formal contract that will allow you to claim the relevant items of paperwork for your move in advance of starting your new role.
I would suggest that you stay somewhere for the initial week or two. There are a number of short term (few weeks to a few months) rental options specifically tailored to international professionals. They tend to be relatively inexpensive and will allow you to be centrally based for a short time while you look at your longer term accommodation prospects. IT Search can provide contact details for providers of this service if needed.
When opening a current account the most important thing is a confirmed address. It can be your current address until you have an apartment here. IT Search can provide contact details of people who can assist in this process if needed
Regarding PPS number etc, this is a very simple process with which I help candidates moving here on a regular basis. You need a copy of your contract and proof of address here and your passport. Contract will be provided either by your employer, proof of address would be a letter from the first place you move to (I know many places that act as halfway houses for people who have just moved here before finding their long term accommodation as per Viva Dublin for example ) and your passport.
You bring these to a specific office in Dublin (Blackhall Place, two minutes LUAS from O’Connell St/City Centre) and they generate the number in days. You can ring and ask for it within two days and they post it to you in a week. This PPS (Personal Public Service) number will allow you to become part of the Irish Taxation system as a PAYE (pay as you earn) employee. More information is available here.
This would very much depend on the package that you want. If you already have a good phone, you may just want a SIM only plan. O2, Vodafone, 3 are all good operators.
This link is a good comparison site for Healthcare plans set up by the State. If you are in Permanent (PAYE) employment, your PRSI contributions (Pay Related Social Insurance) will cover some health care issues. Additional information here.
Longer Term Accommodation
Depending on your budget, family situation, desired location and where you will be working there are many possibilities as to long term rental. The most comprehensive rental site in Ireland is www.daft.ie.
Dublin is moving towards an integrated transport system using “Leap” cards (similar to London’s Oyster Card system). Links of interest related to public transport are:
Each person’s tax liability and take home is different, however this tax calculator is very accurate.