dothackers.net

#1: Are there any missions in this game

#2: Should you do the Vol.2 missions before starting Vol.3?

#3: I'm also curious if the racing time for the courses in Vol.2 matter in Vol.3 because I'm tempted to use the cheat to easily beat them.

#4: Does the cheat works in Vol.3?

The cheat is talked about here

http://www.dothackers.net/bbs/viewtopic.php?t=11762

1: yes
2: you don't have to, but you probably should, or else it'll be a joke later
3: don't be a n00b, just do it
4: never tried, possibly, I don't see why not. (there wasn't really enough time in between games for player feedback to reach time)