The Wiki Extensions run fine on all the versions of .NET that have been officially approved for use with SharePoint. At present, this means .NET 3.0 and .NET 3.5 (from SP1).
Our software does not include any hard-coded file names, so you shouldn't have any issues here. The dynamic path names will also adapt automatically in countries where standard paths obviously have different names.
Yes. We have tested our software on 64bit Windows 2003 and 2008 Servers.
The issue occurs when articles (pages) have been created but not yet checked in. The reason is that SharePoint checks whether the link exists, but on a technical level rather than on a user-based level. To solve the problem, check new articles in after creating them, and then you can edit them as normal.
Remember that the BlueBridge Editor can also be used on standard rich text fields. Please see our documentation for more information: http://wiki.bluebridge.de/documentation/en/Wiki%20Installation%20Guide/Rich%20Text%20Editor.aspx