Please pay attention to this: I do not use
writer2epub but
writer2xhtml written by Henrik Just.
writer2xhtml is an extension of OpenOffice/LibreOffice. Unhappily I do not know
writer2latex.
I can give to
writer2xhtml any odt file to convert and it manages to export to a clean EPUB2 that I can later perfect if need be.
Among the nice features I use often are its ability to append an external css stylesheet and embedded fonts, and its convenient use of style-mapping. The preference panel offers a broad choice of options, among them applying manual formatting (bad), or only style formatting (good). You can also fine tune the splitting of your document and many other things.
I have been using it for the last three years.
For PDF export, LibreOffice and OpenOffice are quite good but they export odt files.
What interest me is exporting EPUB to PDF, so that I can also benefit from the enhancements made using Sigil. Calibre can do it but I prefer using Prince which I find more precise for this task (Calibre is of course much more versatile and can be used for a gazillion other tasks).