I don't have an answer to your second question, but as to the first: you won't see MSXSL in your Start menu - it's a command line program. Assuming you have it installed correctly, open a command prompt, navigate to the folder where your xml and xsl files are, and use this syntax to transform:
msxsl inputXML.xml tranformXSL.xsl -o output.html
where inputXML is the xml file, transformXSL is your xsl file, and output is the name of the html file you want to create. There's also a way to run transforms from within IE6 - I think you just need to open the xml file in IE6, assuming that you have the stylesheet linked into the xml file like so:
<?xml version="1.0" encoding="ISO-8859-1"?>
<?xml-stylesheet type="text/xsl" href="transformXSL.xsl"?>
should be the first two lines of your XML file.