It doesn't "need" to be 3/32, you can run a mixed width drive-train set-up without problems. You'll just have to buy a 1/8" chain. Some say this wears the chain faster, but I never noticed anything on my first conversion.

Also, you NEED to buy a thread-on cog. Your wheelset already has one, but if you want to upgrade get a thread-on track cog. That other cpg you posted is for a free-hub cassette.