No, it is not normal for the WPS light top be red. However, this should not cause you any problems becuase WPS is used only to connect a new device "automatically"; i. e., without requiring the user to enter the network password.
In your case, since the WCB3000N was added to your existing network with all your devices already aware of and connected to it, WPS has no real use for you.
You might check if something has caused teh WPS button to be stuck in the depressed position. If not I'd expect the red light to go green after the WPS function times out due to no network device answering it.
It is not surprising that you have experienced improved wireless performance with the WCB3000N active. It not only provides an additional wireless access point, but it is a dual band device - as opposed to your router being single bad - and this means it can support double of wireless throughput of your router.
