Would have thought a roller be ideal for a Defender
Anything by Devilbiss, Sata and Iwata will be fine. Startingline will be cheapest.
Have seen decent results from cheapo chinesium, but generally don't last.
Not for water based as it doesn’t usually contain isocyanates but check first. Any paint that contains isocyanates requires an air feed mask. Think waterbased sprayguns don’t have any steel parts that can rust
Friend of mine sprayed his Defender with a fast mover gun of ebay and it looks a really tidy job. I have a couple of Sealey guns and no problems with them.