Which PixelFormat to use here - I am currently using PixelFormat.Format32bppPArgb?
Instead of PixelFormat.Format32bppPArgb
i would use PixelFormat.Format8bppIndexed
because of this line: /BitsPerComponent 8
Anyway, you can use other format, it will be converted
Is '/Width 986 /Height 1' is the right image size to use when creating C# Bitmap?
Yes it is: width=986 / height=1
Only if you want to create a Bitmap
respecting width and height in Postscript file