You only need to set up a static ip if port forwarding, not for UPnP. But from my experience with users who have Westell devices, they are much better port forwarding. Apparently Westell's UPnP is not reliable. I'd suggest it would be better to forward a port. Look for Westell on this page http://portforward.com/routers.htm

No setting up a static ip will not affect anything else "unless" your ISP does not allow static ip's. But that's not common. I have a static ip, but yet my external ip changes from time to time which depends on the isp. I've never looked back since port forwarding.