A bit off-topic, but it might be helpful, I usually create a custom mini-game called "Wedge's Building Team". Its invite only, I spawn with a wand, printer, hammer, wrench and rocket launcher. I use player spawns so I spawn near my build. I usually do quake-like player so I can run quickly around my structure, but if I need to jump, I just use the normal player. I turn off fall damage as well.
The wand lets you break stuff faster and I use the missile launcher to test my structural integrity, since there are certain ways you can build that makes structures invincible to most weapons, even rockets.
I've got no clue how to adjust jet rate. I usually use the free camera to move around, but if I don't have admin rights I use a flying carpet if I need to move far away.