or what preposition would properly be used there if not faoi...le, perhaps?

Anyway...I've rather decided that Gaelinn rolls off the tongue a little easier than Gaeilge. What I'm wondering is, if I start using Gaelinn am I going to have to explain it each time to non-native speakers, or is it fairly well understood that that's what it means...

I didn't have a problem with the word, but then again I did't have any problems with seancló - which for many people seems to be an insurmountable obsticle...

If you're going to say "Gaoluinn" (nó Gaelainn) -- the Munster word for Irish -- perhaps you'll consider tweaking your Irish to go along with it:
http://groups.yahoo.com/group/TYIMunster

We've a fun new thread going on just now where we're taking stories from Anseo is Ansiúd ( http://www.gaeilge.org/AIA1/ ) and changing the "standard" Irish to Munster Irish.

I am looking to learn "standard" Gaeilge. Seeing that there are Uster, Munster, Donegal-are there more?
Is it possible for others to understand "standard" Gaeilge?

Donegal, Munster and Connemara are the main dialects, with subdialects in each (just like english). standard gaeilge is like standard english...no one speaks it exclusively as their native dialect, but it is what's taught in schools, used for publications, etc...

so, yeah...you'll be understood...