Unfortunately there are very few Abarth Grande Puntos about so answers maybe few and far between.
I'll try to answer your questions.
The Grande Punto and Mito share the same chassis with the Vauxhall Corsa of the same years.
I would imagine the 170 Mito dampers would fit the GPA but as to the DNA adjustable bit working on the GPA
I seem to remember when the 170 Mito came out it was just the rear dampers that were DNA adjustable.
The chassis including suspension on the A500 is Panda based and is different to the Fiat/Vauxhall chassis so parts will probably not interchange.
Even the wheel specs are different, 500 are 4x98, GPA/Mito are 4x100