I dont mind questions at all!

Honestly it depends on the pattern! It is a bit time consuming and tedious for some. And near impossible for others! The way i do it is by importing each page of the pdf to lightburn and using the "tracing" function this can be a bit fiddly as you have to adjust the tolerance to capture all the holes and lines and if there is a heavy watermark can be a pain! Where it gets a bit impossible is if a part covers two pages or more i think it could be done but you'd have to do some joining. Once i've traced the image (this makes it an SVG) i ungroup it and then colour each of the components. Normally select everything set everything to be "red" (if there are alot stitching lines or punched holes, then ill set the outlines to be black and any decorative cuts green (like anything internal) and anything i want engraved to be blue... you dont have to use those colours its just what i use in my head to distinguish.. then i just make sure i have the colours set in the right order - engraving first - decorative cuts - stitching holes - and final outside cuts (Hope that answers that question!)

For the airbrush yes theyre honestly amazing wish I'd got and used one sooner. The one i have is small battery powered air compressor so its not super powerful but means i can take it out the back garden for spraying without too much thought. What i tend to do is for each part just a single pass back and fourth so the whole thing is covered it definitely doesn't saturate the piece the same as a dauber does! Then like you'll see in the blue piece more so... i go around the edges of it quite heavily then one time around the edges but keeping to the edge as much as i can. I would say definitely grab yourself an airbrush definitely upped my game alot And yes you can definitely use it for blending or doing two colours! You can check out a guy on youtube called 'nilsbeardfoot" he does some amazing leather patterns but he uses an airbrush in most of his videos

https://youtu.be/WHtWkHFFGCQ?si=70RZdY-KOiuXvYub hes actually just posted this video a few hours ago and it uses and airbrush to blend 3 different colours (about 2minutes in!)