surely before the new year (most probably, Dresden will know more) but if I were you and if you wanna play just play the current version. Next one won't have many changes and it will be technically save game compatible (probably, Dresden will know more).
Steam: steam has 3 parts 'cause you can't upload large packs and so it has been divided into 3
TWC: twc has 2 files 'cause the first one contains db, txt, ui, scripts (so things sensible to changes) while the second one has startpos, textures, models (less sensible to changes). They are not conflicts, they are overwritings, so everything is fine. You can merge them but there is no reason to do it 'cause nothing will change.
If you haven't already done it, revert to old manager: Go to Rome 2 on STEAM/Right click/Properties/Betas/Select the beta you would like to use/launcher_release_canditate.