Fenders: without a doubt, Planet Bike Freddy Fenders. They are durable, offer good coverage, and fit well on the Cross Check.
Rack: I have a Jandd Expedition rack. It fits and works well on the Cross Check. It is a longer rack than most, so for those concerned about heel-strike issues (given that the Cross Check has shorter stays than a touring bike), the Jandd Expedition rack works well.
Given that, if I had it to do over again, I wouldn't even get a rack. In fact, I don't even use my Jandd Expedition because I got a Nelson Longflap and no longer need the rack (though I'm hanging onto it for now). I've done over 2000 commuting miles on my Cross Check, about half of which was without the rack but with the Longflap. I've found the Longflap is the ideal commuter bag (at least for me).