The following link includes an image of a cup from 1800s England which was used for hot cocoa. The trend of drinking hot cocoa in the nineteenth century in part drove a market for porcelain/ceramic tea sets and chocolate pots.

https://janeaustensworld.wordpress.com/2008/08/09/hot-chocolate-18th-19th-century-style/

This is most likely a reference to someone originating from the British West Indies- the territories in the Caribbean which were colonized by Great Britain, until decolonization in the 1960s and 1970s.

https://en.wikipedia.org/wiki/British_West_Indies

Earlier in the chapter, it is stated that the time is evening. One might be under the impression that tea time was limited to the afternoon. However, times for tea were changing in the early 1800s, with references to "afternoon tea" as well as "high tea" which occurred later in the evening.

https://www.britainexpress.com/History/tea-in-britain.htm

Here, Arthur's reference to green tea as "poison" is strange even to Charlotte. Yet green tea is confirmed to be popular in England in the 1800s. In support of Arthur's point, a text called Ms. Beeton's Book of Household Management published in 1807, which includes many recipes for various beverages, noted that "strong green tea is highly pernicious [harmful], and should never be partaken of too freely."

https://qmhistoryoftea.wordpress.com/2015/02/25/englands-green-and-pleasant-tea/

I like that poet is Capitalized. I just enjoy the word poet.