Just as with the established journals, organizing it isn't that influential and relevant compared to actual editorial board; and it would be likely or even expected that the board of a publication organized by some university would have just a couple members from that university and dozens of respected scientists from outside.

It's generally not considered conflict of interest, as the boards transcend single institutions and their members tend to be individuals in the stage of career where their individual reputations that matter more than the reputation of the institution they "represent".