SwissModel models are threaded against a template. In this case the homologue has 31% identity, which isn't great. The template is 6TP3 which has a rather high R_free of 0.32 and it's solved at 3 Å, ...
The documentation for the PDB module in biopython, which you have tagged, is very clear about how distances are measured between two given Cα atoms.
To find out the secondary structure and interactions between strands of a sheet, you may want to look at the header of the PDB. This is the stuff before the ATOM/HETATM entries. SHEET entries are what you are ...