Hi David. Hope you don't mind if I make a few comments on your post. In answer to the first question you pose, I think the I Corinthians passage is presumed to be refering to a "worship service" in part because of I Cor 11:18 which makes it clear that the context is the coming together of the group. Personally I think it is question begging to translate ἐν ἐκκλησία as "in church" but that is how it is usually rendered. I would prefer something more neutral like "assembly". The other element which could be pointed to is the phrase κυριακὸν δεῖπνον φαγεῖν (1 Cor. 11:20) - which I spent some time discussing in my paper. If this does indeed convey the meaning "Lord's Supper" then this would be another good reason for regarding this as a "worship service". I tried to suggest that this is not necessarily the case but I am very much aware that many would disagree.
You comment that "many in the Apostolic era had "all things in common" " but I think it is clear from Paul's comments in I Cor that this was not the case in the Corinthian community. Other than the early chapters of Acts, I cannot think of any other early Christian writings which seem to presume this model of community but maybe I have missed something.
Your other question is easily answered. The translators include "this" in I Cor 11:26 because it is in the Greek text! The phrase is τὸν ἄρτον τοῦτον. I have checked the TR, WH, SBL, UBS and NA and they all read this. Neither does the UBS or NA28 give the omission of the demonstrative as a textual variant so I'm not sure how the table you included in your post was derived.