I play on GameCube so how would I do v1 timing? Am I just screwed,I think at the moment I should just keep track of my final end time from each section of a run cause trying to do v1 timing on gc is just idk

Yep,its the in game timer+time you spent during a pause

Dreamcast version just means the original version that was just Sa2

Sa2b and all the ports of it are just the most common ways to play the game,but also dreamcast version does have several changes to certain things within levels(some bad some not so bad). sa2b is definitely more enjoyable cause dreamcast controller has deadzone or if your playing dreamcast version on pc the level design and visual changes can sway people's choice of what which version to play. usually sa2b is preferred version to play and speedrun.