It's a cool season grass, and will be very early to start its new growth, so you want to prune it back anytime now. In my zone it gets pretty ratty over the winter, so I cut it down every year.

If it's comfortable in its location, you wouldn't need to divide it for several years, unless it outgrows its space.

In your zone, it will self seed, but not intrusively, and it's a good way to get new plants. It tends to start volunteers near itself, rather than long distances away. You can prevent the self seeding by deadheading it before the seeds ripen, but, in my opinion, this is the time it looks the best. The volunteers are easy to deal with. I just let them grow, and then move them or pot them up and give them away.

It's a great grass...one of my favorites. It can take light shade nicely, and actually does better in fertile moist soil than poor soil, as long as the soil drains well. It doesn't like to sit in water. It's also a very nice container grass. The blue foliage looks great in a terra cotta pot.