DMSrabbit, it's terribly disappointing when eggs don't hatch. It sounds like you had a lot against you to start with.
But try not to give up right away. We all buy thermometers on trust, so our first hatches are the ones that show us if the thermometer is correct. Too slow to hatch: it's reading too high. Too early to hatch and perhaps crooked toes: it's reading too low (and we therefore set our temperature too high). Unfortunately yours was way out so it resulted in no hatch.
It's true the GQF thermometers are unreliable. The glass (which is unmarked) can slide up and down against the card (where the markings are). That's about as el cheapo as it gets, but if you get a decent thermometer there's no other reason why the incubator won't work reliably.
If it was me, I would buy a more expensive incubation thermometer and try with cheap eggs next time. If the hatch rate is good then trust that thermometer. If not, work out by the hatch results whether it was too high or too low, and try another batch of eggs, adjusting the incubator temperature upward or downward. If that result is good then mark on the thermometer what the setting is. (That's if it's not digital.) Once you know what setting the incubator needs you can make just about any non-digital thermometer reliable, as long as you mark the glass. After all, we only need to know one temperature... The perfect one.
As for hygrometers, I never use one, and have good hatch rates. But if you're concerned and plan to hatch expensive eggs then perhaps it would pay to have one. I just follow the instructions that came with the incubator, and don't have humidity problems.
