Possibly A Returning Player - A Few Questions

[Niwashi]

How is the game's population in terms of lower level characters/classes? Are there still enough lower level folks out there playing to be able to find the groups necessary to run the require dungeons and trials?

There still seem to be quite a few new players at least on Coeurl, where I play, plus there are people who may have reached endgame on their primary class, but are going back to level up additional classes and need lower level content for that.

The main boost in availability for low-level dungeons/trials, however, is due to the Duty Roulette. Players can get extra rewards (tomes if they're on a level 50 class, GC seals and extra XP if they're still leveling up) if they let the Duty Roulette choose which dungeon or trial they'll run next, and its first priority is to finish off groups for every dungeon someone has queued specifically for. These extra rewards are available at least once a day for anyone, more often if they can fill the currently most-needed role (which is usually tanks, occasionally healers). This encourages even players who have passed that content to keep going back to it, so newer players can get complete groups.

Is the group finder tool cross server?

There are actually two different group finder tools, so the answer is both yes and no.

Duty Finder, which you use to enter dungeons and trials, will match you with people across all the worlds in your data center if you queue there with less than a full group. Ultros, for instance, is in the Primal data center, so you could be paired with people from any of the Primal data center worlds (Behemoth, Brynhildr, Diabolos, Excalibur, Exodus, Famfrit, Hyperion, Lamia, Leviathan, Malboro, Ultros).

Party Finder, which lets you get a bit more specific as to what sort of group or run you're looking for (and isn't limited just to joining dungeons) is server specific.