I'm new to sabers myself, waiting on my first order to arrive, so I can't answer all of your questions but I think I can help with a few...
Illuminated AV switch - I think you may be confusing the Aeon LE V3 with the regular Aeon LE. Two different models. The regular version appears to not have a sound option at all while the V3 version has the sound option. (the illuminated AV switch is an option for the Obsidian soundboard) The V3 version does indeed have the illuminated AV switch option, check under the sound menu.
Aeon LE
http://www.ultrasabers.com/Aeon-LE-p/aeonle.htmAeon LE V3
http://www.ultrasabers.com/product-p/aeonv3le.htmAs for the light of the blade "flaring out" I don't think it really does that as much as the pics you're talking about. There will be a little bit of flare, like from a flashlight, before the light tapers off a bit. Go to the gallery section on the forums and you can browse through a bunch of pics that people have posted. That'll give you a better idea of what it'll look like in person.
As for the allen wrench, I'm not sure of the exact size... I've seen it posted somewhere a few times but I can't recall where exactly... but I know it's in standard size and not metric. If you're in the UK you might want to spend the extra $1 just to make sure you get the proper size and have it ship along with your saber. It'll save you a lot of $$$ if you do that now rather than end up having to go back and order just an allen wrench later and then have that shipped to you by itself.