To avoid the gaps you can line them up with an overlap.
You can adjust the vertices of the model slightly to help facilitate this. The most natural-feeling way to do it in Blender is by using the Sculpt mode.
You can use a Boolean addition operation to then make the two models a single piece of geometry. Or not bother (if you are printing on FDM or at 100% infill in resin, it won’t really hurt either way).
Overhangs were the biggest issue I found. So much so that I moved back to a 0.4 after a month of faff trying to find settings that would compensate.
I use my printer mainly for minis, and figures that would print supportless on the 0.4 nozzle needed huge amounts of supports at 0.2 in order to print without missing chins etc.
That said, the level of detail that I could achieve was better, particularly on the hair, but not enough to compensate for all of the extra faff and wasted plastic.