Yeah thhostels meantioned above are all central. Litton lane is well priced.
For clubs temple bar is the place top go always busy.
To meet the locals on a friday or Saturday night go to Dawson st. a few good bars therethat are very popular with the dubs. Cafe en sein, samsara would be the two big bars.
Buses will get you into the city centre but if you want to go direct to your hostel get a taxi.
you can pre-book from these guys www.easycab.ie just email them and ask for a set price.
Camden st is another great place for bars and clubs. lots of live music.