Maybe someone could explain the etymology of 'damhán alla'? Looks like an interesting one.
Despite damhán by itself meaning “young bull”, my guess would be that damhán alla is a worn-down version of “wild leaper” — the arachnid damhán being related to damhas, and alla coming from allta.
No, damhán is a diminutive of a word that also means "ox", but both the "spider" meaning and the "ox" meaning derive from an older word meaning "beast".
Why is the mh in "damhán" pronounced like an English "wah" instead of a "v" (For example, in English "snámh" sounds like "snáv"?
I'm no expert but I think the MH is pronounced as a W before a broad vowel, and as a V before a slender vowel. At the end of a word it can be V often (snámh, lámh, talamh) but I think it could vary.