To check how many people are in your current zone, you can just type "/sea" and it will tell you who else is in that area. You can also type "/sea region" to find who is in all of Jeuno(Ru'lude/Upper/Lower/Port). To search for a certain area, go to the Menu -> Search -> Area, then scroll through the regions, and pick the areas, and you can search them like that. I personally don't know the typed out commands for those so that's what I do.
To search for your level range, as in who is seeking around your level, you can also type "/sea all 34-38 inv"(inv meaning people that have their flag up). And you can judge from those results if you can make your own party.
Try this website also, so that you can see a list of where you will possibly be going to camp at your level.
http://campsitarus.blogspot.com/
Really an awesome site.