The only confirmed connection methods for the non-Steam versions are LAN and direct IP. During the GOG Summer Conference Swen tweeted "Make sure you pay attention to @GOGcom Galaxy!" and a link to GOG's Twitch.tv page, so that suggests maybe the plan is to eventually support that.
The global chat is not dependant on Steam at all. A couple weeks ago Larian was considering what they were going to do about the chat, since if it is kept for the release version, they will need to set up additional servers.
There will be some kind of lobby list but no details have been announced (like whether or not it will use Steamworks). Larian did say in the D:OS chat a few weeks ago that they had some very big news related to the lobby list that they couldn't talk about.
Presumably an announcement of at least some of this is coming soon, before the deadline for choosing where kickstarter backers want their digital version(s).
