Newby Questions

[Chess Ref]

1st year VB official. We are already starting scrimmages this upcoming weekend, so I would like some real basic help here till I gain some knowledge and then i can terrorize everybody with my little knowledge.

i will be working the Down, R2. What are say the three main violations that occur that i would have to call ?

Also what are three most common mechanics that a R2 uses ?

Yes I know I should know it all but it ain't gonna happen by Saturday so I figured start with a little bite and i will go from there.

For example in basketball the most common mechanic I used was hand up ,open/closed fist.

Also I found out that travelling was a violation/ mechanic that I would usee over and over.
Thanks for any and all feedback

PS whats up with the Felix Unger outfits out here in California ?