hi,
this video is good starting point
http://www.youtube.com/watch?v=g44Ww2bg2_E. have a look to the wiki too, you will find a lot of answers there.
calclight: used when editing maps. the engine uses "light maps" instead of dynamic lights and they have to compute after the map was modified in editmode.
machinima: movies made inside a computergame, we have the moviecube mod for that. not finished yet.
PAS consists of several sub projects.
*FPS (the standard game mode with multiplayer support)
*SSP (a mod for sidescrolling jump'n'games games)
*RPG (a mod for roleplaying games)
*kartmod (this is from the sauermod project, playermodel sits in a vehicles, usefull for kartgames)
*MovieCube (a Machinima plattform)
a happy new year. offtools.