The specific language "this is the order after which I am called" appears to have reference to his statement in verse 44: "For I am called to speak after this manner, according to the holy order of God, which is in Christ Jesus. ." While the language is very similar, the first reference appears to be related to priesthood authority, and the second to priesthood position. We should remember, however, that there would have been no discernible difference for Alma between these two concepts. His priesthood was his calling and position, and his calling and position were his because of the he priesthood. In this verse he is simply emphasizing a different aspect than his earlier statement.
Social: Alma gives a list of people to whom he is to preach. The general idea is that he is called to preach to everyone, but the artistry of the speech places this idea as an expansion of multiple paired sets of opposites. Alma says that he is called to preach "unto all" and then defines "all" as: "both old and young, both bond and free; yea, I say unto you the aged, and also the middle aged, and the rising generation."
It is unclear why Alma repeats the general contrast between old and young in the expanded age generation phrase including the "aged…middle aged…rising generation." What is most fascinating from a social perspective, however, is the middle contrasting set: bond and free.
Since it is abundantly clear that Alma would be speaking to those who are literally old and young, we must assume that his call to preach to "bond and free" was also real. Since Alma is called to preach in the land of Zarahemla, we must assume that either this is pure rhetoric, or there actually were bond and free in the land of Zarahemla. It is hard to make the case for pure rhetoric, since the statement has no rhetorical force if it is not a possibility. For the rhetoric to have any power, it had to have indicated a possible condition.
This leaves us with the fascinating possibility of slavery in the land of Zarahemla. This would be in direct contrast to the Zarahemla of King Benjamin where Benjamin had prohibited slavery (see Mosiah 2:13). If there is now slavery in the land of Zarahemla, it must be seen as one of the several cultural imports that have accompanied the adoption of other foreign ways, such as the wearing of costly apparel.
Literary: The particular phrasing "bond and free" no doubt owes a debt to the translation of Paul. Alma will repeat the "bond and free" phrase in Alma 11:44, but in that verse will also give a "male and female" pair. In particular, the doubling of this phrase clearly shows the literary debt to Paul:
Gal. 3:28 There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus.