Feeding too heavily right now is bad, although organics are always OK. If you want to feed, the cycle would be April to August or so.

The brown's frequently caused by dessication--the soil freezes, but the plant gets the occasional period above freezing and is slightly active. Heavy mulching helps this, and I use 3" of hardwood mulch on mine with compost as well. You can also spray with Wilt-Pruf, but that should wait until temperatures drop.

To prep for winter, before ground freeze water the shrubs thoroughly as well to make sure enough water is available, and also to slow down the freezing cycle a little. You can also wrap the shrubs in burlap if you want (use posts, don't wrap the shrub directly) and that'll help protect from colder winds.

As they mature, everything you do is less necessary. Mine are age 3 and going through the winter (in PA) just fine with no damage.