If you are using Windows, the LaTeX extension in Inkscape has to be installed separately along with another bunch of software including: ImageMagick, pstoedit, Ghostscript, GS view, TeXtex. There's a guide here if you want to try to install those. However, despite following this guide, I haven't been able to get it to work with the newest version of Inkscape 0.92 running on Windows.
You can save yourself some trouble by using LaTeX Preview and set it to SVG, and then download the generated SVG to use in Inkscape.
If you want to turn the SVG glyphs generated by LaTeX Preview to paths so you can see them/edit them, then use the Edit Paths by Nodes Tool to select each glyph one at a time and click Edit > Clone > Unlink Clone.
As for invisible strokes, just remove the stroke and fill in Inkscape. The path will still be there.
Example of LaTeX Preview generated SVG glyphs, turned to paths, and no fill/stroke, over a visible background.