EDIT: Wrong issue, posted wrong response...
Check for any extra particles in C:>FreshWater>media>particles. If there are any files with _1 or any number, delete it. FH should open then.
As for a map limit, I'm unsure on the exact number but I'm going to go with 40-ish, because at one time (tho it was long ago) I counted about 30 portals in my Cape, and some of them were floating off the island. Don't take my word for it tho XD, I could be wrong.