Hmmm. Well, without giving to much away.. Yes, some Thomas (not much) but strong hints at more to follow. Yes - Jim Dasher features a fair bit. Yes Kaspar makes an appearance.
For me the book was very obviously a piece to set the scene for things to come and felt a bit rushed.
The first few hints of more non Midkemian elves and more non Midkemian dwaves are reinforced, albeit briefly.
Your comment on being obsessed got me thinking... If R.E.F can team up with others to write companion pieces (e.g. Murder in Lamut) who do you think would make a good candidate to work with R.E.F on an Elf / Thomas centric companion piece.
IMO there is huge, untapped, potential in exploiting Thomas's unique heritage and abilities.