1. Bambu seem to be good if you just want a plug and play solution, however they are expensive. I personally use an ender 3 V3 SE, and it has served me perfectl

1. Bambu seem to be good if you just want a plug and play solution, however they are expensive. I personally use an ender 3 V3 SE, and it has served me perfectly well 2. I use blender if I want to make something artistic looking (works fine on linux), and onshape if I want to make something technical (web based, works on anything) 3. thangs.com is a good aggregation site for models that pulls from places like thingiverse and printables. Printer files are usually STL or STEP for the models themselves, then you use a slicer such as cura to convert it into a printer-specific file, which is .gcode file usually, which contains printer movement commands. I've not seen any proprietary files for specific printer, but I may just have missed them