Ean - not sure, but I think it's just EEN
Iefan - an f in Welsh makes a v sound (it's the ff that makes the f sound)
Ieuan - yeah, it's close to Ewan
Ioannes - I don't know about that one, I'm not that familiar with Greek
In case you're not aware, the num pad on your keyboard does shortcuts to pretty much everything. Make sure your num lock is on, and you press and hold Alt while you type some number which corresponds to something. Then let off Alt and it magically appears. It's fun to play around with. For some reason 130 is é, but 160-163 are the rest of the lowercase vowels. The uppercase and some other vowel accents are in the 130s and 140s.
**Vita Brevis, Ars Longa**