Will you be printing them yourself or sending out to an agency.
1). Whilst its normally recommended to draw full size and scale viewports for printing, with 3D prints, in my opinion its better to draw at the actual finished size required, one can set TC to scale 1:6 someone else will have to comment as I've never tried it.
2). Probably most 3D printer slicing programs will accept .stl files which v20 pro will 'save-as', as to the slicing software, I'd recommend using one recommended by the printer manufacturer, some have their own software, others will recommend one which is known to work with their printer.
3). Pitfalls, I'd guess the main one being overhanging parts, some software may be able to compensate for this by adding support material, but if you have overhanging portions of the part it may be better to build in supports, this will give more control over where they are, if you can design it without needing support material - all the better.
Avoid very fine detail if the printer cannot print it as its just wasting time and could cause streaks when extruded.
4). To be honest I'd just looked on some forums, especially one from the makers of the printer and ask questions when required.