Yes, the "slender" vowels e and i change some of the consonant sounds: S->sh; c->ch; d->j; dh->y; r->th
Also second a is silent; it's just there because you can't change from a broad consonant (a, o, u) to a slender one, or from slender to broad across consonants.
Slender: your mouth is more closed to say it; broad: your mouth is more open.
From a nice summary of this and other pronunciation rules, by VarsaTinyArnen here -- scroll about halfway down: https://forum.duolingo.com/comment/35280755/Tha-G%C3%A0idhlig-snog
If you are addressing your friend, you say "a charaid". If you are talking about a friend, it's "caraid". They're not pronounced identically: "charaid" has the 'ch as in loch' sound, but it's a little hard to hear on some of the audio, I've found.
A bit more on "a charaid". When you are addressing someone, you use the vocative, which lenites the name, in this case, "caraid". If you were addressing someone named Padraig, you'd say: a Phadraig.
Hope this helps.
When you are trying to type the Scottish Gaelic, how the best way to type the grave accent mark over the "o" when using an American English keyboard layout?
Side note: I'm presuming that the British English keyboard layout is the same, but thought I'd be specific. :)
On a Chromebook, the default input is US Keyboard, but if you go to Settings - Advanced, you can add the US International Keyboard (and easily toggle between input methods if you enable the input method to be displayed on the tray); with the International selected, you can create accent marks simply by pressing the apostrophe key while simultaneously pressing the letter you want to accent. For a left leaning accent (grave mark), press the grave and tilde key in the upper left instead of the apostrophe. Not sure how this works on other keyboards, but it works great on Chromebooks.
It must be me, but it took me a while to realise that the audio was not saying Cabbage, which, anyway would be càl. The 'r' needs to be stronger, and, I am used to hearing the word, normally in the vocative, a Charaid, but never heard it sound like a cabbage before. Anyone else have problems or is it myself going deaf?