"Tá sé ar intinn againn" is not accepted???
Why is "éist" not accepted here?
Because to form the infinitive, you must use the verbal noun.
Are there certain verbs where the verbal noun is just the bare stem (I'm thinking "rith")?
Yes. rith is one.
Why is it "leis" rather than "léi"? I'd've thought feminine would yield the latter.
It is always leis an for with the. Léi is with her