You make perfect sense - I get just as confused as you.
I'll try to answer some of your questions, but I've only been diagnosed since last August; there are a lot of people here who know a lot more than me.
First, I think you can divide MS medications into 2 broad categories - those that treat symptoms, and those that try to treat the underlying disease. An example of the first group would be Neurontin or some of the anti-depressants for neuropathic pain. Another examples would be medicines to help with spasticity or stiffness. An extreme example would be IV steroids which help with reducing the length of relapses.
The drugs that try to treat the disease include the popular DMD CRABs - Copaxone, Rebif, Avonex and Betaseron. These are the popular front-line treatments. But there's also Tysabri, Rituxan and some others. In general these aren't used to treat symptoms, but to try to limit future relapses, and slow down the progression of MS to some extent. Which medicine does either one of these the best (or at all) is open to a lot of debate.
So to answer your question, yes, each individual needs to find the right combination of medications. Yes, many people take both a DMD and medicines to help with symptoms on a regular basis. (I only take a DMD currently, since my symptoms have been bearable). The answer to the last question is a little complex. The body has a certain capacity to heal itself; so in the absence of relapses or disease activity, then it's possible for damage to heal and symptoms to go away. So, yes, indirectly the CRABs and other immuno drugs can cause symptoms to go away.
To help prepare for the CRABs (if that' the route you're thinking), I'd read up as much as possible; the internet is pretty good for this. Many times the choice comes down to how often you want to inject, and what side effects you can tolerate. This site has a separate message board for each medicine, so you can find much information there. The drug manufacturers' websites also have useful information, but you will have to read this through you own filter. Of course they're each going to tout their drug as the best. As far as medicines for symptoms, you can post any specific questions you have here, and I bet you can a lot of good answers.
Hope this helps.