He's not talking about the 722TS.

The 721 and 725 are identical aside from the 725 having smoothed out welds and an aero seat tube. Geo and construction are exactly the same. The 721 is actually a little bit lighter.

Leader aluminum frames require a zero stack headset, like the FSA ZS3.

Choosing a bottom bracket will be determined by what crankset you'll be using. Don't pick out a BB beforehand.