You asked if Saturday would be better, and I think it probably is because everyone seemed less rushed when we mentioned the weekend.
If we start around ten, that gives plenty of time for coffee, a quick review of the plan, and a little flexibility if someone shows up late.
For food, I would keep it simple with sandwiches, cut fruit, and maybe pasta salad since that holds up well and does not need much attention.
If you want help with the table setup, I can bring the extra folding chairs and that long blue cloth from the storage shelf.
I would also label anything that goes in the cooler because people always forget which container is for drinks and which is for ingredients.
As for the playlist, keep it quiet early on and save the louder tracks until the cleanup is nearly done.
That usually makes the whole thing feel easier and less chaotic for everyone.

You asked whether the garden bed should be moved before planting, and yes, I think shifting it a little closer to the fence would make watering easier.
That side gets steadier light through the afternoon, and the tomatoes would probably do better there than by the steps.
For the herbs, I would keep basil and parsley together because they seem happier when the soil stays evenly damp.
If you still have the small labels from last spring, use those instead of tape because the tape curled up almost right away last time.
Also, I would not plant everything on the same day.
Start with the hardy ones first, then wait a week for the more delicate plants so you can see how the soil settles after the first watering.
If you want, I can stop by Sunday morning and help line up the pots, check spacing, and make sure the taller plants do not shade everything else by accident.