The VCD standard requires CBR encoding. As for your other question I have always used 4:3 and never had any problems.
depends on your plans for the movie...if you want to play it in a standalone, it must be constant..however there are some dvd's that will play vbr vcd's (they are typically called xvcd's)but those are very few.. as for aspect ratio it depends on the aspect ratio of the movie you are ripping..if widescreen or amaphoric it will be 16:9 and video source needs to be set that way or your picture will look stretched. but in 'other' settings there is a video setting to convert 16:9 to amaphoric or full screen..it's the 'no margin full screen' setting..i use it a lot...works great.
