So when will the new walkers an lvl 3 troops be released?

If you look at the upcoming section of the FFG website, they have a status of the new expansions.

The German Special Ops were updated on 04/25/2011 as being "On the Boat" from the printer. This process usually takes "4-6 weeks" for the product to arrive to the FFG warehouse. Once shipped from the warehouse the status will once again change. The shipping from the warehouse in MN can take "7-10 days" and longer for Canada.

So if we do the math the product will arrive at the earliest late May and the longest mid June. It will then take another 7-10 days to arrive at your local store. So at the very earliest you will see the new expansions starting in early June and the latest should be mid June.

The newest of the expansion, just showed up as being at the printer and can take "many months" before they change the status to "On the Boat".