Roam around? Not that I know of. I think the concept of having those bars or whatever were not implemented on SIA planes or at least no on Biz class.
As for noise level, I really cant remember enough to comment on this. I cant recall how noisy 747 and I took the flight 6mths back, cant really remember the noise level since I've travelled a couple of times since then. I also had the headphones on most of the time, the biz class headphones cover the entire ear so U barely hear anything with it on.
Pretty expensive tix though. The A380 is a bit more exp then most other flights. The round trip cost around $5k. Good thing I wasnt the one paying