There's been countless threads on sub 10 and sub 12 amp failures. Unless you're an electrical engineer and can figure the circuit out, the replacement amp is your only recourse and they're not cost effective. I'd recommend a twisting one and a half somersault. The degree of difficulty isn't all that high but if you stick the landing it'll be worth it.
You're room is about the same size as mine. A larger Reference speaker will work fine (8" drivers or larger). The biggest issue you'll have is finding a sub big enough to fill in the bottom end.
A H1 will go a little higher, a little lower and a little louder. That being said, the 100's are a good surround in their own right. I actually use a pair on my back porch for 2 channel.
Many here have used them. My experience is that they sound pretty good but won't reach "concert" level volumes. They're cheap enough to experiment with also. Be sure to get a stout power supply, at least 5a, or you'll be bass shy.