fightingfalcoln,
Welcome to multi-player.
The "latency" or "lag" is basically the equivalent of "pinging" the server you are looking at. And yes, 800 is pretty bad. That to my knowledge is not controlable from your end.... it is mostly reflective of the path your bits are taking to get to the server and back. But it MIGHT have something to do with your ISP and how they have your connection set up.
Yes, that is the Teamspeak that people are using.
As to why no one on the "SimV server" ........ if you look at all of the FSHost based flight servers they are very "underused". The busiest ones (use FSHostSpy to find them) typically have no more than 30 people on at any one time in the whole world.
If you want "busy", you have to go to VATSIM. That uses specific software to link up (Squawkbox). At any one time there are something like 100 ATC people working and many, many hundreds of people flying all over the world. The problem is, VATSIM is VERY much like flying in the real world. So you'd best be able to fly like a real pilot.......procedures and charts and such.
Watch this forum for the various "Tour" flights that happen. At those times, there are small groups of SimV polits flying. But usually no more than a dozen. max.
For example tonight at 9 PM Eastern USA Daylight Savings Time there most likely will be a "Tour" continuing that is called the "South American Tour" organized by Jared. This is the seventh weekly session....and we are flying out of Mexico City to

???. Watch for Jared's posting later today.
best,
.....................john