Once you have finished the search for accommodation, I recommend you doing tours during the weekends. These tours can be a bit expensive but they will be a good experience and you will see amazing places. Normally the tours take all day, they start from 6:30 to 8 and finish at 18:00 - 20:00.
In Dublin, there are a lot of places to visit everyday, after the working hours at the company. Interesting places to see are Richmond barracks, phoenix park (where you can see deers in the nature) or the archeological museum.
These are some interesting links to book tours: