Agreed.
Agreed.
I mostly don't agree.
Lunars, but as far as I remember, in quite good terms with Lhankor Mhy, so with most of local sorcerers. As lunars, they will have bad relationships with lots of people south of Tarsh.
Feared by even the lunars and hates by almost everyone, agreed.
On them, I don't know.
As far as I remember what Jeff told about them, they are the most numerous, are seen by other Orlanthis as good Orlanthis with strange magics, so not as heretics, and are a closed culture (earthly equivalents we spoke about are Druzes Hazaras and Yezidis). And as a closed culture that don't proselytize, they are, as you say, very unlikely to teach sorcery to anybody else, specially with their endogamous castes.
As inhabitants of one of the sixths, probably well seen by citizens of the Holy country, and unknown to other dragon pass region inhabitants.
Yes, but you also can have other Issaries that are sorcerors.
I think you forgot 3 of the groups, and perhaps the 2 largest: The dwarves, the trolls and the non troll arkati.