Should there be a dash after the t?
No; there’s no hyphen before a capital letter.
Article plus maculine noun starting with a vowel.
Why is the t there again?
Because Iodálach is a masculine nominative noun that begins with a vowel, and in this sentence follows an and is not part of a prepositional phrase.
Why is it not "i bMeiriceá"?
Because m doesn’t get eclipsed. (It’s m that eclipses b, e.g. i mBarbadós).