Hi Steve, I can safely say Scribus is an excellent DTP application. It bears more resemblance to Quark and Indesign which are the industry standards (note: de facto standards from good marketing and not from professional opinion) than MS Publisher, which is a but a nipper in comparison. They all pretty much do the same thing though. Scribus can also create interactive PDF documents
All DTP apps work in their own hideous proprietary file formats. When working between apps I find a mix of EPS and unlocked PDF's a reasonable way to transfer text and graphics. Post on here if you get stuck in scribus (SVG for vector graphics of course).
As a quick start there are two important things to note in professional document design, the first is size, the second is colour! Size comes as is, if you make an A4 document, it will be A4! Colour however is where it gets tricky. Make sure you have your Monitor, and printer ICC colour profiles installed. Within Scribus, select EXTRAS from the toolbar, then Colour Wheel. From here there are three fantastic modes here for selecting a complementary colour scheme; Complementary, Split Complementary, and Tetradic. Always useful when working with existing or new company colour schemes.
Cheers Rich