I’ve never had any issues with it, but I haven’t brewed anything this year due to lack of free time, so maybe/hopefully just a bad batch from SafAle?

Refractometers are one of the most misunderstood tools in home brewing. The two biggest mistakes are using the sg side of a dual brix/sg scale (the conversion is non-linear, and the scale will likely become increasingly off between the two the higher the gravity), and using one like a hydrometer, ie simply subtracting final from original gravity. Instead, only use the brix side of the scale, and use a calculator such as this one to determine the actual specific gravity/abv once fermentation begins: https://www.brewersfriend.com/refractometer-calculator/ (don’t worry too much about the Wort Correction Factor.) Do that, and your refractometer will be your best friend.

I had to do that recently, ended up being easier to just temporarily change the password to something short on a pc, then change it back after.

Depends on your meadmaking technique, but the process is likely pretty similar. Apple juice, like honey, is low in assimilable nitrogen, so you’ll want to add a nitrogen source (DAP, fermaid, generic nutrients, etc). It is high in sulphur containing compounds, which the yeast will use in lieu of nitrogen, so if your nutrient levels are too low, you’ll know from the smell. The lower gravity of apple juice also means the yeast will be less stressed, so you won’t need to age nearly as long to get a drinkable product. Also, I find a neutral ale yeast to be preferable to a wine yeast, like Nottingham or safale S-04.