Pervaya is a feminine form of "first". Just like in English, "one" and "first" are different words. As far as I know, the only qualifier for joining the merchant class was showing capital. There were plenty of Jews, that were merchants, in many cases outnumbering gentiles within towns in the Pale.
You are correct, it refers to merchant class and would be used in a form of "1st class merchant", "daughter of 2nd class merchant", "brother of 3rd class merchant", "grandson of 1st class merchant" as an official title. 3rd class merchant class existed until 1860's. The title was held while one was able to show certain level of capital, otherwise you revert either to a lower guild or to your previous social state, for example to meshchanin (city dweller).
The rules regarding unlimited travel, rights, etc varied over the years. At some point a Jewish merchant had a right of unlimited travel, at other times the law changed and they could no longer stay outside of the Pale of Settlement for longer than 6 months, even if they owned a property in a city in one of the internal provinces.