STT - How will ROI change if I increase my ICM edge?

[Rambling Wreck]

I apologize if some one has already done all this analysis and there is already plenty material available.
I had posted this in STT but I thought it is more appropriate here.

Question 1:
------------------------------------------------------
Is payout directly proportional to prize equity?
That means if I will pass up 0.2% edge and make decisions that have 0.5% edge will the increase in payout be proportional to this additional edge?
I am assuming the answer is yes since the prize equity accounts for the pay structure.
If the answer is no then my model in Question 2 is invalid. You may point me to the correct analysis.

Question 2
-------------
Assuming the statement in Q1 I computed increase in ROI if I start making decisions that have greater edge. By that I mean I will pass up 0.2% edge and make decisions that have 0.5% edge. According to the assumption I made in Q1, I say that my payout increase by an amount proportial to the edge% I increased.

Another assumption is that I have my opponents figured out (calling ranges) and I make perfect decision every time and play infinite games.

Here are my computations-
On a N person table E% increase in prize equity means increase of N x Buyin x E/100$ payout (Using the statement in Q1)

If the rake is K% and my current ROI is R% (based on buyin+rake) then the new ROI is
ROI(old) + 100*((N * E)/(100+K))

Question 3
-------------
If you agree with model in Q2 would you agree with following statements?
Please note that the increase in ROI is independent of ROI and is equal to
100*((N * E)/(100+K))
At a 9 players table with 20% rake it would bring
100x9x0.5/(100+20) = 3.75%
My initial guess was 4.5% but the rake changes things because we don't have stake in rake but it is counted toward
ROI computations.
At 10% rake the increase in ROI is 4.1%.
Points to take home:
1. Increase in ROI is independent of current ROI.
2. If some one has low ROI it making these small edge decisions can almost double their ROI.
3. If some one is at medium-high ROI (20-30%), because the increase in ROI is smaller portion of their ROI, they can make decisions that have very little Edge% (0.1-0.2%) without losing too much ROI. Decreasing edge from 0.5% to 0.2% only decreases their final ROI by 2.5% (the increase in ROI is only 1.63% instead of 4.1% with higher edge). But they might be able to play more hands per hour and increase their overall returns.