There is a limited time skin for Luke that is possible to earn in game now. If you unlock it then it will always be unlocked so the limited time part of it simply means that it is only unlockable for a certain time period.
To unlock it you need to just need to complete the first challenge about killing thirty enemies in any game mode, which is really easy and can be done in 2 matches of blast, meaning it can take less than 20 minutes to finish the challenge.
The last little bit of news is about stats. Right now they are actually tracking our stats for when they finally release the stats page which will be very similar to the one from the first game.