I find Orbitz is fine for hotel+flight tickets, though since Evo Japan isn’t being held inside a hotel like Evo Vegas is, your hotel room choices are basically anywhere that’s convenient and (hopefully) cheap. If you’re going to Tokyo, you’re going to need to navigate the train system anyway, so as long as you know how to get from your hotel to Akihabara Station you’ll be fine. Plug the addresses into Google Maps and it’ll give you the most efficient route. Handling the Tokyo train system is another entire topic in itself.
And make sure you select the kind of room you want. When you plug in dates and click search, the absolute cheapest options for stay in Tokyo are going to be capsule hotels, which are quite limited in how much luggage you can store and sometimes kick you entirely out during the day while they clean up, so don’t jump at the cheapest option unless you’re sure the room is roomy enough for your needs.
As for meeting up with others who are going, no idea. It’s six months away and not on many peoples’ radar quite yet, not to mention that the high costs involved are going to make most people stay home as compared to standard Evo. Still, if you’re going anyway, then the earlier you book, the better your available options are. If you’re lucky, you can get a package deal that makes staying a week or longer not that much different a price than flying in just for that weekend.