Costs Fatigue, Variable and Auras - ratcheting-up

[Plane]

If you have it set where you pay 2 FP (+1/min) per 1d the aura does (activates for full minute) then assuming you start at 1d, to increase the damage of the aura:

1) do you need to turn it off (free action) and on again (free again) and pay an entirely new amount of FP (like 4+2/min) to establish the new die (2d) amount?

2) can you just wait until the next minute-tick and opt to pay the higher 2/m fee instead of 1/m fee?

(this seems to bypass initially needing to invest 4 instead of 2, so maybe it could cost the 2pt diff for 1st min?)

3) could you, prior to 60 seconds of use, without needing to flip the ability off/on, just pay the difference, but it only lasts the remainder of the unused 60s?

It seems like with Costs Fatigue you could view the initially higher cost for the 1st minute as being half the "usual cost" (which applies to all subsequent minutes) being applied as normal atop a "half surcharge", with that surcharge being key to being able to use the ability, so if you did something to increase the ongoing costs it would probably require paying the surcharge too?