1. Do you have a older version of the map? Is it named something different if you do? Spacing in words count as well. Could be an actual server hiccup. Sometimes maps eat characters and it'll show someone logging in via group or arrival and not leaving. Are you using the map files theirselves that you made or are you using the .fhm file you exported? There's.. actually a lot of possibilities with this one.
2 Means you have a conflicting object group probably? I have this problem too sometimes. Are you putting the .fho files in exports? Are you using the map in exports and all or are you using the original copy you have in terrains? What I mean is, do you have the .fhm for that map in your exports?
Firstly try taking everything out of exports if you still have the original map in map maker. This could solve problems 1 and 2.
If that doesn't fix anything try re-exporting the map(s). See if that works.
And if you're still having problems move some files and test things out. Try moving the .fhm file to terrains. Or maybe move the .fho files to your object folder. It sounds weird and abit less organized then shoving it all in exports, but I've solved problems this way for others before. Watch what you move though if you don't know what you're doing.
3. I had this problem personally and it confused me forawhile. When you login the FH client do you cpaitalize your name at all? Preset files are case-sensitive. SO for example I logged in as zombiekitteh adnd everyone saw me as ZombieKitteh (the case I originally registered with). So when I exported my preset it was zombiekitteh_1.fhp and since I was ZombieKitteh to everyone else, they didn't see it but I did.
4. The server has been crashing and having lag spikes. The site was down yesterday too. Give it tiem I'm sure it'll solve itself over time or staff are working on it.