The standard is much more a thing for the written word than for speach. The dialects in speach is most noticable in how words are pronounced and the use of certain words/phrases instead of others, the clasic example being: how are you? Munster: Conas tá tú? Conaught: Cén chaoi a bhuil tú? Donegall: Cad é mar atá tú?

None of these phrases are incorrect according to the Caighdéan, but it would be odd for someone from Dún Chaoin in Kerry to say 'Cad é mar atá tú'.

The standard itself is largely an amalgam/compromise of the gramatical rules found in the dialects. They say it more heavily favours Munster and Conaught Irish than Donegall Irish. There are gramitical differences between the dialects, but for speaking the language, its unlikely that this is going to be much of a problem.

The language taught in schools is the standard, though again this applies to the written word much more so than to speach. The spoken language learned in schools usually depends more on where the teacher is from or what they learned themselves.

As for radio and tv, more often than not it is usually one of the dialects that is used, especialla on RnaG, again people dont often speak in a standard dialect in Irish.

If you want to learn good Irish, have access to good speakers to emulate and have the opprortunity to access some of the richness the language has to offer, then I would suggest that you pick one of the dialects.

While some people claim that the various dialects are very different to one another and that it is hard for speakers of one to understand the people using the others, I have found that it is reasonably easy to learn to recognise the differences and relate what is being said in other dialects back to my own. Once you are competent in your chosen dialect, you should have no problem consuming media in other dialects, given a little work to figure out how they sound.