devtrackers.gg
Grass does recover if you are not regularily walking on it.
Sure, he just needs to send you their Configs and Storage folder.
Contact their support, it's a hoster issue.
RAM depends on map size, up to 200x200 works fine with 4 GB, assuming you use a Windows Server.
That's a database corruption which cannot be fixed, you can either restore a backup or delete the .db file of your savegame (or keep it running corrupted), but in all cases without restoring backup your statistics (used for laws) will be broken.