As for Wurmhoels, the method to create them is kind of buried in the interface right now. Need to fix that. Essentially, reserve some pieces (or not) then go to ...rescon?m=wurm
Choose the "where" and "which" and then reserve that selection. You'll be given a confirmation and a link to use when uploading your "wurmhoel" piece.
For those who don't know, a Wurmhoel is a HyGrid piece that "bridges the gap" between two or more older HyGrid pieces. It acts as sort of a "dimensional pinch point", allowing disparate HyGrid squares to become part of the same neighborhood.