There is no replacement for cheese. I've never found one. Just kiss it goodbye, be strong for 6 weeks or so, and after that you'll find you don't even miss it. It's just a whole lot of fat, salt and cholesterol that you really don't need.
To add protein to your sandwiches, use nut butters, or tahini, or an easier way is to use a dip, home made or store bought. Hommus, chunky Thai, Praise 97% fat free mayo is dairy free, and check out Tofutti Better Than Cream Cheese, it's dairy free, and handy for making your own dips. Also plenty of dip recipes in the Vegetarian Chatter threads.
Soy yoghurt replaces yoghurt quite happily, but you could also try having some canned fruit, or a soy/rice milk smoothie. (if you don't like most soy milk, try Bonsoy or Vitasoy Soy Milky, they're both quite neutral tasting)
Nuttelex, your dairy free margarine, is the best choice, i think. I got hooked on it long before I gave up dairy, I just love the taste.

To up your calcium, go for unhulled tahini, which is a great source. White beans and leafy greens are good too. Also, if you still eat meat, increase the amount of meat you eat that is cooked on the bone, especially boiled-bone broths, as you can really get a lot from them. But you may need to boost your Ca. I have always done it anyway.