Hi, thanks for your comments, they will definitely be helpful in getting the article to a point where it's appropriate for more general audiences and not just trained linguists. To answer some of your specific questions:
 fómhar has [u:] in some dialects because the rule that mid vowels are raised to high vowels before nasals (including the formerly nasal mh) applies to ó in many dialects. This reminds me that I didn't discuss that raising in the article at all, so I'll add a new section about it presently.
 F and bh/mh/v are often pronounced with the bilabial fricatives  instead of the labiodental [f, v]. Unfortunately, the published sources aren't very specific about when which versions are used. The same is true for palatal vs. palatovelar (not that there's a huge difference between the two in the first place  any individual speaker probably uses both interchangeably without even hearing a difference)
 Sometimes the standard orthography does a very poor job of representing a particular dialect's pronunciation of a word. In the dialect I got the info from, scanradh happens to be pronounced as if spelled scamhradh. The pronunciation of cam is /kaum/ per the discussion of lengthening/diphthongization before fortis sonorants.
 Exactly how the fortis and lenis sonorants differ changes from dialect to dialect, as I tried to show in the chart. There isn't one unified pronunciation of the two types.
 Images of the vocal tract like the one you link to are fine for consonants, but not much use for vowels as the differences between nearby vowels are too slight to be easily seen in them. Also, they belong more on the pages about the sound in question than in this article.
 I'm sorry if your heart sinks at the word "largely", but this page really isn't intended to help you get from spelling to pronunciation. (That's what Irish orthography is for.) This page is for describing how Irish is pronounced by native speakers, regardless of the spelling. The realizations of sh are also discussed at Irish orthography, though some discussion of the alternations between [h] and [ç] would probably not be amiss here.
 I'll see what I can find about stríoc. There's no epenthesis when cn gn is pronounced cr gr, because epenthesis is found only in Munster, and cr gr for cn gn is found only outside Munster.
 "...[at abstract level] vowel-initial words... all begin with either a front or back glide that triggers either palatalization or velarization... Is there a way to determine what is being triggered in each particular case?" Well, from the orthography, yes (if it starts with e or i, palatalization is triggered; if it it starts with a, o, or u, velarization is triggered), but from a purely phonological point of view, no. It has to be included as part of the lexical information of the word.
 "Alternation" in the table refers to the fact that some forms of a word (e.g. the nominative case) have one sound (e.g. a long vowel) with other related forms (e.g. the genitive) have another sound (e.g. a short vowel).
—gr