The acoustic qualities of an oversize bucket and the same atmosphere as a fridge.
He's going to see Rammstein. None of those things will matter anyway… 😉
Since you're standing (assuming you have standing tickets – they no longer let people with seated tickets into the standing area), then earlier is slightly better, but I usually arrive at around 8-ish unless I'm bothered about the support.
There will be loads of signs pointing you towards carparks. These are usually in all sorts of places, and tend to be operated by Salford gangs who "persuade" local businesses to open their car parks for the purpose (persuasion = not fire bombing them). Never had a problem parking in any of them.
Or, there's a below street level (not underground, as it's by the river) NCP about 5 mins walk from the main entrance, near the Harvey Nics.