This winter, I am going to be getting my bike re-painted, want a different color and have some corrosion that needs attention. It is going to be sprayed with Cerakote. I am also going to be doing a complete drivetrain upgrade in the spring. With this, I will be leaving behind the square taper BB. As a result, from my research, this needs the BB shell chased and faced. Should I have this done before or after paint? If it helps, the coater I use won't have any issue masking off the face for media blast and paint.

Side question related to this upgrade path. If I want to install a 9 speed Tiagra cassette, circa mid 2000s, what am I going to need for spacers on an 11 speed freehub body.