1) it is worth the download, IRC is the only P2P i use and is the best one i have used.
2) it is easy once you get the hang of it, IRC isnt hard, just different.
3)yes file sharing is reliable, i have been frequenting some of the same channels for years. Also, there are multiple channels for whatever you want on several networks.
As for how to do it, do a search on this board and here is an
IRC FAQ for leechers.