for the first point: I kinda misread it even by the end it seems; the 100-125% part of the heat gauge is darker and it looks like a second gauge. it's hardly a major issue but I kept wondering how I could fill it up. I guess having that bg color for the 0-100% range and an even deeper one for the 100-125% range would help make it read like a single gauge?
for the second: I suppose either would be fine to be honest! a dinky-er sfx or something.