Why put engine flush in? You not going to remove it before it goes on the rollers???? I have never used engine flush in my car and Mark @ Saxon Motorpsort commented that he hasn't seen a bottom end so clean before (expect a new bottom end).
All I do is change the oil after every trackday or 3months which ever comes first and make you feel better the oil I use is £50 for 5 litres!
With the petrol you might as well run it on what ever petrol you have to see what power you usually have, I've always filled my car with super unleaded or now I'm commonly using V-Power from Shell as it's the closest petrol station to me and the prices are the same as tesco..... the joy of living in the valley's
It will take a few tanks fills for the ecu to adjust itself to the new higher octane petrol