
Time is 800 build points divided by build power. Drain is mass and energy per second while it is building, so more build power finishes sooner and costs the same total, but pulls harder on the economy.
Carries 8 where the other three factions’ T1 transports carry 6, for the same 120 mass and 500 health. Planning a drop, Seraphim need fewer airframes to move the same army, and that holds at T2 as well.