I have to say your first point sounds to me like a pretty good reason for arriving on 24/25th!
You should definitely arrive on the 24th or earlier if possible, but do not arrive on the 25th. You will have a bad time.
Here was my experience on the 25th:
1) Woke up, left alburgue I stayed at night before, and went to go to pilgrim's office to drop off bag since I was leaving later that day.
2) Got stopped at cathedral square (they were stopping all people) and told I couldn't go through the cathedral square with my backpack, so I took the long way around to get to the pilgrim's office (this is coming from the Stick and Roots (or whichever it's called) albergue a short ways up the trail to Finisterre).
3) Got to Pilgrim's Office and saw line out the door and a bit down the block for the compostela and the line for the bag drop off went to the opening of the courtyard (but remember you have to go up a flight of stairs to get in. Went "screw that" and went to a pension that I'd stayed at before I left for Finisterre and talked with the land lady.
4) She remembered me (I directed some business her way and stayed there 2 nights) and said yes, of course I could leave my bag there, so I did.
Basically since none of the arriving pilgrims can get into the square to take pictures and wait around to meet people and soak in the general awesomeness of completing the journey, everyone immediately goes to the pilgrims office to get the compostela after learning they can't get into the square, so it's completely slammed and takes a very long time to get through the lines. I'd talked to a couple that had to wait an hour and a half just to put up their bag, and they hadn't even gotten the compostela yet!