Sorcery, Energy Reserve, and Recover Energy?

[Pseudonym]

I am wondering if there is a Recover Energy variant for Sorcery. I am guessing if there isn't one already statted out, it would simply be:

• Regeneration (Fast) 50 pts
• FP Only (-0%)
• Magic (-10%) because it doesn't cost FP like sorcery.
• Potentially tempered with Takes Extra Time to make it slightly slower to get rates of 1 FP/2 minutes (-10%) or 1 FP/4 minutes (-20%)

On the last point, I am not sure if you can use takes extra time on a continuous ability, so I also calculated full prices using a power function trendline for Regeneration (Somewhere between Fast and Regular):
For 5 minutes, I get 38 and change, or 39 points.
For 2 and 1/2 minutes, I get 42 and change, or 43 points.

So this ability might finally cost:

• 45 points to recover 1 FP/Minute
• 40 points to recover 1 FP/2 minutes (using takes extra time)
• 39 Points to recover 1 FP/150 seconds using a logarithmic extrapolation
• 35 points to recover 1 FP/4 minutes (using takes extra time)
• 35 points to recover 1 FP/5 minutes using a logarithmic extrapolation

Which of those sounds like the most appropriate values to use to simulate that ability? Or am I completely off base and missing a critical piece of the calculation?

Finally, would it make sense for an ambient power like this to be switchable like the other sorceries, therefore giving it the 80% discount for other switchable sorceries and taking away the ability to maintain other spells while using it?

For reference, the function I used to extrapolate the price:

http://i.imgur.com/NDpf0gR.gif

And one small addendum by the way, I couldn't find this while searching but it seems like the discount for very fit specifically excludes magic, but does the FP recovery benefit of Fit/Very Fit benefit energy expended for magic purposes? And does it help with Energy Reserve, or vanilla FP only?