1) No, using the same switch, router won't give you the same viruses. (Unless they are some new ones that infect the router firmware. Doubtful, but possible I suppose.)
2) Try running Combofix on all your computers.
Areca ARC-1300 is a SAS Non-RAID HBA. Drivers work ok in windows, cause all kind of IO errors in linux when used with MD. FreeBSD has no support as of yet, areca still promising drivers. :(