I have never seen skip tooth in .325. What is the advantage (except for the guy that doesn't like to file)?
Ship chain can have several advantages, the extra space between cutters allows more room for chips during the cut. Having only half the cutters reduces the cutting force required. Some guys use it so thay can run a longer bar than the saw is rated for.
I've found on really soft and wet woods, it makes a huge difference in cutting speeds.
Never used the .325 skip, to hard to find locally, I stick with .375 & .404
Ed