No, please feel free to book any accommodation that fits your needs. Waikiki is a very small area, and all hotels and accommodations are within walking distance of the events.
October in Hawaii offers warm, summer-like weather with daytime highs in the mid-to-high 20's (Celsius) and cooler evenings in the low 20's (Celsius), though it's still within hurricane season, with rain often falling as brief, nighttime showers.
The bride and groom request that guests abide by a "cocktail/semi formal" dress code.