DOHC 2.5's are only on 98's ans early 99's. All the rest (including 2002's) are SOHC. You might have been thinking of 16 valve valve engines being DOHC, but they are infact SOHC. If you take the valve cover off they are indeed SOHC. THough there are 2 camshafts because the engine has 2 banks of cylinders.
Inthe snow the cars are great. You do need to remember that AWD does not increase the traction of the tires, so turning and breaking are unaffected (though the AWD aids the antilock breaks by keeping individual tires and complete axles from locking) you biggest advantage is under acceleration. You get little slip (unless you choose to) you just drive from a stand still. With dedicated winter tires its more like driving on gravel than snow and ice.