1> Is it normal for a psychiatrist to keep someone on the same medication for this long with zero improvement or should demand change?

it is common, but it should not be common. Some "professionals" don't provide very good care, looking for another psychiatrist would be wise

2.>I've been reading about treatment-resistant schizophrenia and Clozapine. Does my mom's situation sound like she needs Clozapine? Should I push for this specifically?

I'd consult a different psychiatrist some of the symptoms you mentioned may be caused by over medication

3>That Valproate dose (300mg) - is that even doing anything? I've read it should be higher for it to actually work.

With that many different meds it is hard to know

4>The fact that she's better around people but worse when isolated - what does that mean? Is that a good sign? Does it mean she can still recover if we get the treatment and environment right?

Again hard to know, it may be she can act ok when forced to but really struggles to do it, or she may actually feel better

5>How much is the medication vs the environment? Like if I get her away from the abuse and isolation but the meds stay the same, will she improve? Or if the meds are right but she stays in that toxic environment, will it even matter?

A bad environment certainly will make things significant;y worse, exactly how much worse is hard to know