Have you ever played a kart racer before? That's a valid and frequent tactic. You almost always want to snag a weapon that is commonly grabbed or right in front of your opponent to deny them a weapon. Otherwise you're just asking to be shot.
Hell if this is happening to you and you have an opponent ahead of you do what I do and aim for the lesser grabbed weapons (the ones on the fringes or further from the boost).
No. Online is broken because only some people seem to be affected by the collision catapult. So much as get rubbed by another racer and you slingshot into the wall at a dead stop, often backwards, or you fly right off the track if there is no wall. --- On Sara Silverman's attractiveness: "I am not into bestiality, so no, I am not attracted to that god damned centaur" -- Phantasium