Parking is available at the venue since the venue is on a church property. There should be more than enough parking available and no need to look for street parking.
Feel free to wear cocktail/semi-formal attire or whatever makes you feel best.
If you are traveling from north Orange County, please keep in mind that traffic on the 5 freeway on a Saturday of a holiday weekend is heavy. Estimated times can be double or triple the non-traffic time.