I do not know what the upper commands represent - I believe most are automatically written into your config file through CoD itself, depending on which servers you play, or have played in. Some of them could also be related to Seismovision, a useful tool which allows to fast-forward demos.
vid_xpos represents the screen location of the left side of the window in terms of width vid_xpos represents the screen location of the top of the window in terms of height
Both depend on the resolution you are using in-game.
seta sys_sysMB and seta sys_vidMB I believe these values are related to whatever value you have set through com_hunkmegs.
com_hunkmegs allocates X amount of RAM to UO. Recommended setting to around 1/2 of your system's current RAM.
Note: Since UO is an older game, it will not identify a value higher than 512 (MB). Unless your system has less than 1GB RAM ( which is highly unlikely) make sure to set this value at 512.
