A while ago I stumbled onto a wikia page for Star Wars Episode 7, listing actors and the characters they will be playing in the upcoming film. I took this with a grain of salt, though have monitored the page for changes, in which I have seen none. Almost 3 months have passed without any changes to the page, but a few days ago, imdb confirmed that Andy Serkis will be playing Supreme Leader Snoke, the wikia page (found at disney.wikia.com), has listed this casting for months now. So, if we presume that this means all of the names on this page are correct, we can learn several more characters who actors will be portraying...
1. Max Von Sydow: Vicar Montross
According to the page, Max will be playing a supporting character in [Star Wars: Episode VII — The Force Awakens](tag:711158), who allies with Rey. In addition, the page shows several concept arts that have previously been linked, presumably connected with him.
The image below comes with the following caption: "Vicar Montross sits inside Rey's house."
2. Domhnall Gleeson: General Takin
There is not alot listed for Domhnall, except that he will be playing General Tarkin. Although recent rumors have suggested Gleeson to possibly be the son of Luke Skywalker in Star Wars Episode 7.