Although I have no experience of your actual hull I am a racer and boat builder.
A counter rotation Fleetmaster should have been very cheap - as others have said it makes it very difficult to set up as the prop choice is very small indeed. I would have recommended a Sportmaster not a Fleetmaster for this application.
A Tempest prop is usually a very stable prop - see if you can get a Laser of the next pitch up and try that.
The chine walking especially on slowing down I would suggest is as much prop as anything and until you are not hitting the rev limiter I wouldn't change anything else. Chine walking is also a feature of high performance boats - different props can help but it is always a combination of factors.
With high performance engine mounted higher on the transom we mount motors in the centre - Ospreys may be different.
Is the steering hard to turn with the trim all the way in - try trimming the motor out a little and it should improve.
You need to work out the slip for the different setups, record the speed (at least two directions to remove tide and wind), RPM and enter the results with the gear ration here: Prop Calculator
Bubbles in the steering will not make the steering heavy but will not help with the chine walking.
The difference in the amount of heel from left to right turns is due to the offset of the motor and the direction of the prop - it is reversed for right hand rotation motors.
A 25" motor set up for speed is always going to end up high on the transom and will definitely not help with the chine walking - I would always recommend 20" maximum with a R/H Sportmaster, with the motor you have it will always be a compromise and never ideal.
I hope the above is some use to you and is just my opinion.