The Historic District

Hello all...long time no see. (Not a Covid-19 joke)
I have finally arrived at the point of beginning siding replacement and painting and have a few questions about things.
To begin, I am using regular wood "style 105" drop siding, also known as German siding or Dutch siding. It sits flat against the framing with no sheathing underneath. I am adding Tyvek and then some thin furring strips between the housewrap and siding, and the new siding will be back, edge, and end primed before installation.
My questions are about nailing...to facilitate speed and ease of installation as well as noise reduction for my neighbors I would prefer to use a pneumatic nail gun. Any issues in this? I've never used one so setting depth might be a concern, especially as the studs are old growth and very hard.
Also, what nails to use? I have read preferably stainless steel ring shank nails with a full head and about 2.25 inches long (1.25 inches longer than the siding/furring strips combined)
And my biggest question...should I leave the nail heads just flush and paint over them, or should I countersink them just a bit and fill...and if so, with what? Exterior spackle?

Thanks in advance, and I hope everyone is well. The house is making good headway!
Eric

Eric, I would think the stainless ring shanks would be the way to go and sink and them. I would expect the traditional way of filling would be with putty, but any good quality exterior filler would work, probably much better, no nail pops in a year or two.