Every club will be slightly different but you are mostly correct depending on who or what owns the land/ stadium.
The club ‘assets’ are the value such as the fittings. , air fence , starting gate, probably some structures solely used for speedway equipment and the like. Just be aware that not all track equipment will be owned by the club as a lot of sponsors and individuals provide machinery for the clubs use.
The track name, licence, lease have no moneyterie value .
Any new promoter has to be ‘approved’ by the BSPL ( dont think they have ever turned anybody away )
You are basicaly purchasing the ‘rights to run speedway’ at the venue .