It is not Honorbuddy, yes. But then again, it is just me who developed this, not a whole team of devs... @BoobaFat, the conjuring problem usually occurs when you have multiple food/drinks on your action bars. You sure that is not the case?
Anyway, to your actual questions:
What good is depends a lot on your perception and what kind of rotation you actually want to run. The ones listed mostly work for general purposes, for high-dps you would probably need to do some tweaking based on how you want it to run. "Out of date" doesn't really mean much since the 1.12.1 patch hasn't changed over the years.
Some, yes. Specifically those made by bin4ry and l0ctus are made to work from 1-60.
Not that I know of, at least none specific ones. Again as said, this would depend on your build and how you want it to run.
Mages and warlocks with a tanky pet work the best since they have the least downtime. Mages can just conjure more food/drink and warlocks, depending on level and gear, might not even need food or drink.