I am Volko Ruhnke's medulla oblongata....
Rule 11.3 states that "A maximum of four VP may be scored by the CP player for all of Russia." Does this mean that the CP gets 1 VP for each conquered Russian home area up to a maximum of 4?
Indeed. 1 per conquered Russian home area, no more than 4 total points can be scored this way.
Per 10.1.3, the CP gets 4 VPs at game end if Russia collapses. Is this in addition to the 4 VPs the CP may have gained from conquered Russian home areas?
No, it is not in addition to any amount previously gained through conquest of Russian home areas. The collapse assumes that -- since all of Russia is basically out of the way and has ceded a considerable sprawl of territory to Germany by the Treaty of B-L -- the maximum of 4 points is given the CP player. Thus, Rule 11.3 stands as is: A maximum of 4 may be scored.