Live auction in newark, how it works?

[Su Soma]

Hi, I'm planning to go to the live auction in newark for the first time, and I heard that if i win the bid I will need to make a deposit of 20% of the winning bid, and only certified check and a money order is accepted, my question here, how can i prepare that check in advance if I don't know what would be the winner bid? Cause they don't accept a personnel check that I can write it right away. My second question is the bid starts at $100 most of the time, what if nobody has made a bid, would I be able to get it at any price above $100 or the sheriff will need to accept or reject regardless of nobody has bid on it? Any more details would be much appreciated, thanks!