on limited experience, 720p works almost as well as 1080p giving consideration to how many people will actually view your video on at least 42" full HD any lower than that and 720p shoud do the trick.
also 20fps is the craps (i do animated renderings so on this regards i have quite some experience, go for 24 at least for a more cinematic experience). there is no point going HD ,1080p at that, if you cannot get the fluid movements.
running and talking are indeed basic movements, but a of very different kind. talking might pass on 20 fps but running on 20 fps and it might just seem all like a blur or skippy.
just my 2 cents