I did a spraying course in april and have a full compressor setup etc i plan on spraying raptor in mine eventually but you can just brush it. You can use a stipple roller if you want that effect.
You`ll need to remove rust then use an etch primer or adhesion promoter to any bare metal. Use scotch pads to key the surface, you only need a light key you dont want to go to bare metal (or you`ll need a primer)
Being a 2k paint technically you should be using an air fed mask as it contains icocyanates which really arent good to be breathing. Long term exposure can cause asthma but even short term some people have a bad reaction to it....But as long as you ensure good ventilation and use a good mask you should be ok.
these are the filters i use
https://thefacemaskstore.co.uk/moldex-9230-combined-filter-a2p3r-for-series-7000-9000-easylock/its about as good as you can get without going air fed, general rule is if you can smell paint through your mask the mask aint good enough, i have a moldex full face mask i use with those filters as bad stuff can get in through your eyes and pores,......probably seems overkill for spraying 1 van but good masks are reusable so worth buying as can be used for all sorts of d.i.y such as sanding using different filters.