Reno-Tahoe International is the closest major airport to South Lake Tahoe, however, just be aware that there is no direct flight from PHL. Another option is Sacramento International which is 114 miles to Valhalla which takes roughly 2 hours, which may offer cheaper flights, so it's worth checking. The drive from Sacramento does take you up through the mountain, so we don't recommended doing it at night if you're not comfortable with mountain driving.
Ideally, yes you probably should rent a car to get around more easily.
Yes there are 70 parking spaces at the venue. There will be a gate attendant off the main road to allow access to the parking lot of Valhalla Please allow time for a short walk from the parking lot to the ceremony space.
The venue is a historic site located in the US National Forest. The venue is marked by a sign on the main road and is gated. A gate attendant will let you in. No open flames are allowed on the property and no drones are allowed.
The main tip we have is to STAY HYDRATED!! South Lake Tahoe sits at 6237 ft elevation, so please make sure to drink water and add some electrolytes in. Increasing your water intake before you arrive will help combat any symptoms.