I just emailed Nokian US about the Hakka 2 and the replied and said that they are available (no price mentioned) and they come pre-studded from the factory. They appear to be pretty much the Hakka Q with studs. On their European site they claim 10-15% shorter braking distances than the Hakka 1 on glare ice. Sweet.
As far as sidewall stiffness: Like any snow tire, the sidewalls a fairly soft. The extra tread depth also goes towards making the tire feel soft. If you want stiff side walls get rally snow tires. Another solution (if you are worried about the sidewalls) is to get tubes in the tires. It will give you a little extra protection from punctures and popping the tire off the rim.
If they are priced anywhere near the Hakka 1 expect to pay about $130 ea.
Anyone know if you can put 15" rims on the WRX?