I believe people have said that all the cards will be available once you buy the online version. So I would say don't worry about that. He's just saying one person "hosts" the game, just like whoever invites another player on iso "hosts" a game.One person will own the cards and the other person will not have to. That has been the plan and I do not imagine it will change. I don't think people in the beta have any extra information there.
Unless I'm wrong, in which case someone in the beta feel free to correct me.
The expansions will be sold separately, but hey you can buy them all at once if you want. The main set will be free. There will probably be a couple ways to get the promos, one of which will be beating campaigns.
You can't please everyone, but I do not imagine too many people will be unhappy with the pricing scheme.
If there is a lobby, like there is on Isotropic, will there be an indicator next to each player's name that tells us which expansions they have? As in, if I were to buy none of the expansions (very unlikely, especially if they're reasonably priced), would I be able to see which expansions my opponent has, so that I can pick certain opponents over others based on that info?