Paistaa does mean "to shine" in the context of the Sun is shining, but it also means to cook something on a pan/to fry. "Paista" would be the second person singular imperative, so used like "Paista tuo pihvi!", so "Cook that stake!" (We don't bother with please in Finnish :)) or "Paista jo!", or, "Shine already!" directed towards the Sun.
I found this very useful: http://www.spanishdict.com/answers/166839/how-do-i-put-accent-marks-on-my-computer
A number of people on the main thread announcing the new audio have reported issues with the new audio in Firefox on Windows. The volume issue, though, affects everyone.
Note that most sentences on the Irish course do not have audio, so the lack of sound on any given sentence is not an indication of a glitch.
Duolingo uses the same web template for all its exercises. Because Duolingo was designed to be used with a text to speech engine, in which all exercises in the language that you are learning are spoken, all Irish to English exercises have a speaker icon, and al English to Irish exercises don't, even though the Irish course does not use a text to speech engine, and therefore doesn't have audio available for all exercises.
The lack of audio is NOT a bug - it's a limitation due to the fact that managing actual voice recordings is expensive. The presence of a blue speaker icon on exercises that don't have any audio could be considered a bug - before the last big website redesign the speaker icon was only displayed if there was audio available for that exercise, but it is unlikely that the Duolingo programmers will do anything about it - there are far more annoying bugs that affect all languages that they haven't fixed.
So far, in the discussion threads, the speaker icon seems to correlate to the availability of audio for that exercise (there is no icon at the top of this page, for example). But when you are doing exercises, the blue icon is just decoration - if the audio plays automatically when the exercise opens, there is audio, if the audio doesn't play automatically, then there isn't any audio, and clicking the speaker icon won't do anything.
Edit: The web template has been updated so that the speaker icon only shows when there is audio available.
Like most European languages, the plural definite article in Irish is not the same as the singular definite article.
The child - The children
An páiste - Na páistí
L'enfant - Les enfants
El niño - Los niños
Das Kind - Die Kinder
Het kind - De kinderen
Il bambino - I bambini