I'm no expert, but here are some answers, I believe. Others here can provide additional (and probably more valuable) comments, but here comes mine (just from the top of my head).
Number one: Yes, there is intense research going on regarding the different patterns of MS. Dr. Claudia Lucchinetti (Mayo Clinic) appears to be leading the way on this aspect. She has so far found four distinct different patterns of MS. The researchers are constantly researching and trying to prove or disprove each other's hypotheses. So, yes, they are "on it", as I put it.
As far as lesion load goes. If you investigate and notice closely, for the most part, lesion load is discussed mainly in connection with RRMS, not the progressive MS types. Most of what you are referring to appears to be the discussions and theories that pertain mainly to RRMS.
SPMS and the more progressive MS types for the most part don't even involve lesion load nor inflammation, either. And some types of MS involve axonal damage, sometimes even without demyelination.
The rest of your questions, I think you will find, just goes back to the ever unresolved quandary of MS itself. The more you research (and I personally do advise that you continue to do so), I'm afraid that you may find yourself venturing more and more into the "unknown" and confusing nature of MS. That's why there is research all across the board right now. Nobody knows for certain very much about MS at all, nor can any real correlations be made between lesion load, symptoms, etc. etc.
As far as the "theory" (and it's only a theory) that experiencing sensory symptoms first "may" indicate a less severe course of the disease, I believe that comes from just statistical analysis, not from exacting medical proof. Motor control itself mainly comes from the cerebellum and the brainstem. If you are showing motor symptoms FIRST, it is likely that MS has damaged a portion of your brain (or spinal cord) that is (for lack of a better word) more "dangerous" for damage to happen in. Again, though, try to remember, that this correlation is mainly "statistical", not necessarily a medically known "fact".
As far as "future" attacks? Well, there is a certain percentage of people with RRMS who, after a speculated number of years from being diagnosed with MS, will enter into SPMS, which is a more progressive type. Again, this is a "statistical" observation.
Nobody knows why "anything" might be so. Crummy, isn't it? There are next to no answers to anything in this devious disease, is there?
Hence, why you may notice some of us being so "passionate" at times.
I hope this helps somewhat. Others here will have much better advice for you, also.
EDIT: Oh, another thing I wanted to tell you, also, is to remember that the "immune" system isn't completely what you would think of as we think of it in everyday terms. The immune system is very complex, and also includes "self-recognition" as a part of its function. Parts of the immune system fight off disease, but other parts do other things. There is the innate immune system and the adaptive (acquired) immune system. Actually, is the "immune system" involved in just about all of the MS types? Yes, in one way or another - not in "all", but in most. Sometimes so early on, that it doesn't even seem like it's the immune system at all being talked about, but it is. And is it always the same "part" of the immune system or the same place in the "timing" of what and/or when the immune system does certain things that is involved? No. And is inflammation always involved? No. You might want to do some research about the immune system and how it works. Get ready, though, for another sojourn into deep water! HAH!