The biggest (non) surprise: his teammates are "100%" supportive. I can't find the original Irish mail article anywhere, so you'll have to settle for AfterElton's summary, which quotes from it.

There's a quote in that first link that leads me to believe that he isn't technically a professional athlete, but he is playing at the top level of a somewhat popular sport.

Another reason to love an Irishman!!

The great thing about the article is that it did not dwell on his sexuality, but went on to discuss more pertinent issues to the team and sport! That's progress!

Speaking with my friend in Dublin over the weekend, he had just watched Cusack's interview on RTÉ, and was beside himself with pride and admiration for the man. Hurling is a big deal in Ireland, and Dónal Óg a major athlete. My friend is also heartened that the news has been met with such widespread acclaim and support.

The interview:
Part 1
Part 2
Part 3

The acclaim:
Brave Donal Og Cusack ushers in new era
Cusack's 'outing' a seminal moment in GAA's 125 years
Irish gays hail sport star's coming out
Cusack's giant leap forward
and so on...

Good man. An inspiration. A hero.