Help! Got roped into my first CompREL event. Hi,

Background: I'm an L1 judge. Mostly a FNM judge to help out around the shop and cause rules are cool. 

I've been testing to play in a Super IQ this Saturday. Last minute the store owner contacts me and tells me the judge he had lined up had to cancel on him. Asked me if I can judge the event, but said that I could still play in the event. I'd be on call for judge calls but wouldn't have to do the deck list/deck checks maintenance. (So I can play) I said I'd have no problem stepping up for the event. 

This would be my first CompREL event. I'm pretty confident in my rules interactions (7/10), but less so in my MTR and IPG (3/10)(and don't have the time to cram study it). 

Just wondering A. it's ok for me to do both judge and play, right? B. What are some tips for a first time CompREL?