1. Does that "weapons_ru.properties" file cover ALL a/c in the game?
It should. I mean, that file is mandatory for Starshoy's DGen, since this latter search aircraft weapons in it, and gives error if something is missing. Different for Asura's DGen_mod, which looks for weapons in its own
AllWeapons.dat, then using
[episode_name]Planes.dat as a filter. For Asura's users the file thus becomes just a reference, though important. Megapacks (like TFM) developers should keep it updated, as well as players should add lines related to new planes added.
2. So the entries in the Asura weapons file should basically match the file above, correct?
Yes, they should.
In lack of clear, matching reference, you can always scroll in QMB aircraft preview its loadout options: those are read directly from plane Java code, if
weapons_ru.properties is missing related lines: a lot of errors are possible, from spaces (blanks) inside weapon name (e.g.: "2x Type3"), to incomplete loadout lists for missing Java code of some weapons.
This kind of debugging can be an instructive experience for you; keep in mind that you may always remove that arguable set of two rocket-bombs (issued in 1944) for A6M5 (which is of 1943) as I suggested earlier.