Also, does wikileaks ever spill the beans on other foreign powers, or is it solely US focussed?
They are primarily US and UK but have also released leaks from other countries as well. They are not solely about government but also released information on business and hacking groups. I don't know how well known they are abroad and if there are other sites that host leaked information for other countries. You can see everything on their website wikileaks.org
On the subject of wikileaks...
Wikileaks is not a hacking organisation as suggested by a tweet published earlier. They publish leaked information that is given to them. In the case of this CIA data the story is that it was leaked to wikileaks by a contractor. This is credible, remember Snowdon was a contractor, they can have access to very sensitive and confidential information. Why the contractor chose to share this information with wikileaks is a other question. Perhaps he is a Trump supporter, maybe he was paid by someone, or perhaps like Snowdon he saw this information and felt it needed to be shared with the wider world.
Why did wikileaks chose to publish it? Well that is what they do. Only wikileaks knows if they have information they have chosen not to publish, but on the face of it I find it hard to imagine that wikileaks could not put this out once they have received it. Their credibility would be decimated if it ever came out they held back information like this.
Is wikileaks a Trump/Russia tool? Again, who could know (or would want to know) the inner workings of the mind of Assange, but my personal view is that just because we see sides in this business and want to put people on either our side of Trump's side we should not assume wikileaks is working to the same principle. I suspect they have their own sides and their own agenda that may align with Trump/Russia but could just as easily not. It is certain that Trump/Russia are more than happy to make use of wikileaks when it suits them and timing does suggest that they may have had a hand in leaking this information to wikileaks, and at the very least are dancing a little jig about it right now.