Which Groupset?

I understand that SRAM cassettes will fit a Shimano freehub, but am I right in thinking that they are differently spaced, on account of the 1:1 cable pull (Exact Actuation)?

The spacing on 10 speed Shimano and SRAM cassettes is the same. SRAM mechs and shifters have different cable actuation ratios, so you can't mix'n'match shifters and mechs, but the net result is the same amount of movement per click at the derailleur.