Welcome to the telemac world! There is a great tutorial from the download area
www.opentelemac.org/index.php/training-and-tutorials, TELEMAC-2D tutorial.
BlueKenue can be used for mesh generation and boundary conditions file generation. But it is not the only option. eg, I normally use SMS to generate mesh and export an .2dm file. BlueKenue can import the file and generate a slf file from it.
Fuddaprepro can be used for case file generation and also boundary conditions file generation.
Hailiang