Creating a shortlist for myself here to some handy tools to create tcx and gpx files.
www.coursemapper.com/ (also to reverse and adjust an existing course)
To connect multiple gpx files to one file I use TCX_CONVERTER. In a particular case I converted multiple kml files that were parts of one track each to a GPX files using gpsies file converting tool. Then I loaded the multiple GPX files in the TCX_CONVERTER and exported them as one TCX file.