Unchecking the “has heated bed” checkbox in the printer configuration panel will also unset the variable for bed temperature,
bed_temp, so you’ll get the same inja error. So that would explain why you were having that problem before.
Similarly, if you deleted your second extruder slot you wouldn’t be able to use
nozzle_temp_1, either, since your printer doesn’t have a second HotEnd. So far so good.
We don’t update any of your scripts automatically when you change your printer’s settings, which is why you’ll run into issues like this. We’re planning on having more validation of your scripts and more useful warnings/errors in the near future. Right now, though, it’s important to double-check that your scripts are right for your printer. Fortunately, scripts don’t really change very much, so you’ll only have to do this once.
Not being able to import models sounds like a separate issue. Could you give a video of you trying to import them? Right now we know that if you’re trying to import models with non-ascii file names you’ll have trouble (for example, models in French that have accents won’t load properly).