Chains on the rear will make a world of difference. I use double rings when the ice gets bad, they're also useful in the mud. No way would I chain up the front. I'm sure a little weight up front wouldn't hurt, but adding the chains will easily double or triple your traction in the snow and ice.
I did a little experiment when I first got my chains, I drove into 12"+ of hard snow in 2 wd and went less than 30', made it another 20' or so with the diff locked, 4wd got me a little further in. I had to use 4wd and the diff lock to get out. On went the chains and I circled my front yard, (10+ acres), in 2wd, no diff lock.