I would like to add to this thread. Although I don't own a Focus yet, I have done similar things with a newer F150. Several things run through your cluster and can cause certain things to quit functioning. In my '05 F150, a cluster swap made it so my A/C wouldn't work. To remedy your problems, the cluster needs a reprogram from the dealer. They can't reprogram your miles, but they change the as-built data on the cluster so it will work with your car build.
I would estimate a shop trip to program would probably run about $100. I am not 100% sure this will fix the warning light problems, but this sounds similar to the F150 and that is how I fixed it.
Just an FYI.