Can answer a couple of those points.
Auto is marginally quicker (on paper), not worth writing home about though
The dots.... Utterly stupid, its the only thing I genuinely hate with a passion. You do get used to them and what a dot equates to, I consider 2 dots reserve level. Current prices, from 3dots to full is £126 subject to increase or decrease, who knows.....
Id assume the GT has pretty much the same spec (barring seats and trim) as the Nismo so boot cover, shelf behind seats and a little cubby for a small umbrella, gloves and a spare bottle of your chosen aftershave. Glove box is perfect size for your service book and touchup kit, can even fit you locking nut in there
Centre console has a pop up you can fit a small phone or 2 in and a USB stick for some tunes.
As for your point on tax, mines a 2019 so ULEZ compliant and falls in the £165 bracket, so if thats a factor worth considering a later model.
Overall, I found it night and day over the 350 in terms of refinement, comfort and better performance.