To followup on my own question: "I was wondering about "mono yofo" - is that only Dovor Shebikdusha? - what about serving at a meal etc?"
I saw on the evening following my email, that this very question is asked at the back of the latest edition of Kol HaTorah (referring to daf 13a). [Kol HaTorah is published twice a year by Agudas Yisroel in Europe. At the back, there is a section containing a short Dvar Torah for each daf of the Daf Yomi cycle for that 6-month period].
He says it is a Machlokes Rishonim, and brings a few Ma'arei Mekomos (that I have not yet looked up):
Rashi Nedorim (72b), Nimukei Yosef end Moed Koton, Cheshek Shlomo and Haghos Ben Aryeh in Nedorim, Rashi Gittin 59b
I would still be interested in any of your comments
Kol Tuv,
Mark Bergman
The Mishnah Berurah (O.C. 201:13) states that this applies to a regular meal. [The Rashi in Gitin (59b, DH "v'Litol") which you quoted above seems to say it is whenever a Yisrael and a Kohen divide something, unlike the seeming conclusion of the Mishnah Berurah.]
All the best,
Yaakov Montrose