Welcome, Flex.
The rush at opening is mostly for shade/river spots. Keep in mind that all of the established, permanent camping spots along the river have already been reserved for Tuesday night through the Town of Lyons, and those people will already be set up. So there won't be many river spots anyways. If you can get a spot on the north side of the main path, you'll have some shade at various times. With the expansion of the park, there are more areas to find a good spot. PB has not confirmed a location for the family area either, but my guess would be the far west side by the big playground. So yes, the earlier you get there, the better spot you'll get. But it's a huge park with more room than needed, so even people coming Saturday will find big, open spots.
Camp size is only determined by the boundaries of the park/paths and what you need. If you want to set up a shade tent next to your tent, no problem. There are many multi-person compounds set up.
Visiting other campgrounds is usually not a problem, especially with your LJ Park pass. Some volunteers get a little picky, but most will not mind if you let them know it's just for a bit.
As long as your wife has a ticket in hand, or you come up to meet her, no problem.
I hope you're excited. We love Meadow Park/LJ and can't wait to get back every year.
Author