Bought a used UPBOX, what should I check before first print?

Hi, I just bought an upBox of indeterminate age (but it has a 2017 PAT-inspection sticker on it). I don’t know if it has standard nozzle or any other ‘adjustments’ (it doesn’t have Wi-Fi or spool-extender mod).

I need to buy my first 500g roll of filament, do they come in different diameter/gauge, and should I verify the extruder nozzle is the correct size for the filament?

Thanks in advance for help on these noob questions.

UP BOX use standard 1.75mm filament, it usually fitted with 0.4mm nozzle and ABS extruder.
The filament compartment may not fit spools from other manufacturers, you may need to prepare a spool stand if you are not using the Tiertime filaments.