
Time is 3,600 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.
The only T3 mobile shield in the game, and Seraphim get nothing at T2 while UEF and Aeon field one for 220 mass. It costs 720 for 10 000 shield, which is roughly three times the shield of a Parashield for three times the mass.