"Yon" is a short form of "yonder", meaning "that", perhaps more precisely "that one over there". "Lea" is a meadow.

"For I had a dochter, ane o ma aine"--I believe "dochter" is daughter; "ane of ma aine" is "one of my own" (as you figured, Merry).

"Will you lodge a beggar man? Lassie to my *too row* ray". Here the "*too row* ray" part sounds like "too ra loo ra loo ra", and I would guess it's meaningless filler.

"*With* his tooren-ooren *and* tan ee(?)"--here I have no clue.

I can't help but think this little tiff over "mocking" is a simple misunderstanding/miscommunication. Though Merry is more proficient in her (written) English than what I would call a "poor English speaker", some of her spelling and construction is consistent with someone who does not know English as her native tongue. Perhaps we should allow a little slack?