There is no real difference between streaming over wired or wireless. I've never seen a 404 error in the last 15 years, sure I'm closer to the backbone than most, but if there is an error, just call up your provider and get it fixed.
No, wireless interference is negligible, so even if you have a basic Airport Extreme, you'll still get 54Mbps, IF your connection can go that fast... chances are high you are on a 7-20Mbps line, so even Apple's slowest wireless connection will flood your Mac or AppleTV.
You haven't seen a 404 error in the past 15 years, I find that hard to believe, I had one last week, I was trying to bring up an old news article but unfortunately it had been pulled from the site. Earlier this year, geocities was taken offline, a substantial portion of the Internet just became 404 material. Also didn't gmail have a major outage last year?
As for wireless interference being negligible, I also have to say in my experience that is just not true. In France a lot of people use wifi as their primary means of connecting to the Internet (why I don't know, it seems French telecom has some sort of wire alergy) and while living there I heard so many coworkers complaining about dropped connections. When I was in France I used an airport express to stream to my laptop, I tried to watch the season four finale of Lost and it cut out several times (just as Ben started to turn the wheel, I was so angry) that was with a router about ten metres away, admitidly it was an old building with thick walls which may have caused some interference but still. Also, I believe if you check the airport extreme manual, it mentions something about wireless phones getting too close?