I just rode Wicomico on Friday. Was wet, but there was plenty of traction. The MX tracks were a wet mess. If it keeps on raining it will be a mess on the day of the race. But everyone is on the same track so fair is fair.
As for racing, if there is a bottleneck don't sit and wait, go around immediately. You can make up 15-20 positions just not waiting at mudholes or steep climbs.
Enjoy yourself, have fun !
Tail of the Dragon at Deal's Gap... Avoid it now, do a trackday.
Do not do business with Myrtle West Cycle... Not a reputable vendor by a long shot.