Here at the end of Alma 49, we have two instances of etc. that were removed in the editing for the 1920 LDS edition. Nonetheless, these uses of etc. are not redundant but imply additional, unspecified information.
For the first example, the etc. may be referring to those who had served with Ammon and his brothers in their mission to the Lamanites, as described in Alma 17:8: “and thus they departed into the wilderness with their numbers which they had selected to go up to the land of Nephi to preach the word unto the Lamanites”. As David Calabro points out (personal communication), this first etc. does not generally refer to anyone else who preached among the Nephites since that more general group of preachers is referred to in the following text: “yea and by all those which had been ordained by the holy order of God / being baptized unto repentance and sent forth to preach among the people etc.”
For the second example, the etc. implies that those “sent forth to preach among the people” would have used their priesthood not only to preach but also to do other tasks (such as baptizing and ordaining others).
The critical text will restore these two original instances of etc. here in Alma 49:30 since they are clearly intended. For further discussion, see under etc. in volume 3.
Summary: Restore the two original instances of etc. in Alma 49:30; in each case, the etc. provides a necessary reminder of other, unstated possibilities.