I went from OEM stock to PSS9's so I can't say how the PSS9's compare to M030. My guess is that the PSS9's on soft would still feel stiffer than the M030 simply due to the stiffer springs that come with the PSS9's as compared to the M030.
There really is no single mandatory list of parts for a suspension upgrade. First, you have to decide what you want to acheive and what kind of budget you can afford - then you can start looking at what parts will reach those goals and what tradeoffs you might have to make to keep within your budget.
Also, selecting some parts will require that you install other parts to make everything work so there is a bit of a ripple effect that has to be taken into account. A good example of this is the rear adjustable toe arms. They were required on my setup because the PSS9's allow the ride height to be adjusted beyond the point where the stock part can provide sufficient range in toe adjustment to meet my track alignment settings. If someone had a differnent goal, such as no or only occasional track use, then they might be ok with the stock toe arms and save the money that I had spend.
Take your time and learn, learn, learn. Talk to several shops. See what each of them recommends and ask tons of questions. I spent 3 months learning about what I wanted and another 3-4 months pulling all of the parts together (at a price that I was willing to pay). For example, $2,200 for a set of PSS9's seemed high to me so I waited and searched until I found a brand new set available for $1,500.
Here is a ratio chart for the 996 GT-3 front and Tarrett rear sway bars along with M030 that might come in handy:
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