-break and then continue an extension line- not implemented.
You could use Fixed Length for extension lines to avoid them crossing, but that's a standard only with architectural drawings.
A bit a tedious workaround is to produce a small patch of a solid hatch in a colour of nearly white, just one rgb value off. You can select this with "custom" colour. It will not be visible but appear as white on the print out. If you use pure white/black it would appear black. Place it at the intersection and with Tools - Modify - Order push it between the two extension lines.
This trick is also useful when you want to place text within a hatched area.
In case you haven't noticed it, there is a manual which might answer many of your questions:
https://librecad.readthedocs.io/en/latest/index.html
I will tell the waiter.