1: Legacy Servers are some of the more populated servers, i being non legacy on balmung
2: Server population has nothing to do with Duty Fimder/Dungeon Que time because they pull people from every server to populate your party, that is based on your class. Healers and Tank have slightly faster que times than a DD/DPS would.

FInding a decnt FC or Linkshell might help, or find a healer or tank buddy to cue up with you. Hope that helps