Translation:I hate cats and I like dogs.
Well, my wife has family in Kerry, so I imagine Munster Irish is the only language I would use, were I ever to use it. That is, unless there is a literary standard. I know there is a Foras na Gaeilge or some such. Is one of these dialects considered more appropriate for the written language? Since Irish is one of the working languages of the EU, which one of the dialects are the other languages translated into?
I have the Teach Yourself, actually, though not the audio materials. I can't imagine ever doing anything other than read Irish, but I do find that having an understanding of the pronunciation always helps me to learn a language (I even pronounce Latin in my head, when I read it). The fact that I have never before been able to connect the written with the spoken language in Irish or Scottish Gaelic has, honestly, been a major obstacle before this little Duolingo program, so I will learn what I can from this and then simply read as much as I can.
Sorta. It's really "based" on all three dialects, and therefore isn't similar to any. Munster Irish uses more synthetic verb forms than the Standard, whereas Connacht and Ulster use fewer. As for words, there's dialectal issues with every dialect. You're best bet's to get a dedicated textbook. The original "Teach Yourself" (for which audio files are available online) uses hard-core Cork (a Munster subdialect) Irish. I suggest asking AnLonDubhBeag for more.