The venue is 21+ so unfortunately kids are not allowed to come.
The Circa is also a 21+ casino and hotel
Due to limited capacity, if the person’s name is not on the invitation you cannot bring a plus one.
I would say the best way to get to the venue is to take a Lyft or Uber. The venue is a 4 -8 minute drive from both hotels.
The dress code is cocktail attire, but keep in mind it is still quite hot in Las Vegas this time of year. The venue has an indoor and outdoor space so there will be air conditioning.