2) אורח חיים ד סג
OK. It's a really long Tshuva and i didn't go through all of it but i did skim it. Thank you for the informative Tshuva!
1) It obviously is
not so poshut if it took R' Moshe 10 pages to explain the difference between Kiddush for eating and Kiddush for being Yotzei the chiuv of Kiddush. I think this is a huge chiddush of R' Moshe and i've never heard of it before.
2) Even according to R' Moshe one would still need to make Kiddush again by the Seuda. Does everyone who makes kiddush b'makom seuda with wine do that?
3) I didn't see anywhere (again, i skimmed, so correctl me if i'm wrong) that R' Moshe says that according to R' Akiva Eiger who says that wine is not considered "b'makom seuda" would say that for being yotzei the kiddush of eating it would be ok.
4) As an aside, we really have to know if grape juice is included in wine.
And finally, the Mishnah Brura says clearly that being Yotzei "b'Makom Seuda" with wine is Shas Hadchak multiple times. I don't think we can say something that he doesn't like is L'Chatcheila.