Can’t say that I’ve used a .2mm nozzle… I think the closest you’ll get may be .25mm.
Changing the nozzle is fairly straight forward, but not recommended by Lulzbot… and can void the warranty. I used two wrenches, one that fit the heater block (17 or 18mm) and the other that fits the nozzle (7 or 8mm). Heat the hotend to 165+ (to melt existing filament and any metal thermal expansion), and start removing the nozzle. It’ll be hot so make sure to prepare for final removal… vise-grips or locking forceps can grip the nozzle for removing from the heater block. Protecting the print bed might be a good idea also… I borrowed a silicone trivet from the kitchen.
To re-attach, heat the hotend back to 165+ and finger thread the nozzle to the heater block. You’ve got maybe 10sec before the nozzle gets too hot. Finger threading provides the feedback to ensure you haven’t cross-threaded. Once the nozzle is on, heat hotend to 250 and tighten nozzle again… don’t go crazy since the nozzle can crack and break off. There is a recommended torque, but I can’t remember off the top of my head… could be something like 25 or 35 Nm.
If you can find one of Sebastian’s post, he probably has more detailed steps in his tutorial (listed in his signature).
Regarding your resolution needs different filaments may generate better corners or detail. ABS is probably one of the worst for sharp corner resolution.
The user saramos has done some nice sub .1mm prints with his TAZ… looking up his posts may provide some insight.