Professional Document Formatting

I'm not aware about XSL-FO technology.
I would like to understand what can it do for me and how can it be used.

I have some basic understanding of the principles of XSL-FO.
I would like to explore the samples to learn how to build XSL-FO documents for my needs.

I have some understanding of XSL-FO and I have my document ready.
I would like to format the document to PDF with your Web rendering application.

I'm familiar with XSL-FO and XEP engine, but using the Web application does not fit my needs.
I need a Web Service that can be integrated into my business application to render XSL-FO documents with no need to use Web browser.

I have too large data and/or my data is confidential.
I need a reliable and customizable solution that I can install on my computers.