The ERS is used throughout the lap and is activated in the game by use of the throttle (full throttle). This is transparent to the player, and you have no indication or other means of controlling it in-game. Officially it's about double the power of the old KERS, and can be used for 33 seconds per lap, where the old KERS was about 7 seconds per lap.
You may have misunderstood DRS zones. When you drive around any track you will see the big polystyrene DRS markers boards by the side of the track, and a DRS line across the track at that point. Bear in mind that these are the points that you can
USE the DRS (
if activated), it doesn't matter if you are within 1 second of the car in front at this point, because that 1 second rule refers to the
DRS Detection Zone (not the DRS line).
View attachment 79563
Look at this Monza DRS layout (2012). On the far right (turn 11) is the Parabolica, you have to be within 1 second of the car in front at that detection point, to be able to use the DRS on the home straight, the
DRS Activation Zone (where the DRS line and markers are)
As there a 2 DRS zones, the other one is just after turn 7. To be able to use it, you must be within 1 second of the car in front just after turn 6 (Lesmo 1), to be able to use it on the back straight just after turn 7 (Lesmo 2).
A small green light will illuminate on the wheel when you can use the DRS. I can't remember whether you also get a beep sound at the same time (we did in previous games). If the DRS is open you will see it in the rear view. The DRS is not enabled (for everyone) until lap 3 of the race, or the 3rd lap after a safety car. The DRS is disabled for everyone if it's raining.
Sorry I can't help you regarding horse power at the different fuel settings.
Cheers