Yep the wiper relay is known for going bad for some reason.
Did your other vehicle have a larger than a 2.0 engine? From my observations larger engines take (like a 5.0 V8) forever to fully warm up, but when they do the heat is scorching hot. 4cyl motors warm up faster and produce adequate heater temps. The Focus has excellent heater temp output, like a V6 lol.
It's true that the factory gauge will go to normal (dead center) before the car has fully warmed up. I've seen this on my Scangauge.