Titlepage learning curve

I am working my way through

http://doccookbook.sourceforge.net/html/en/dbc.fo.style-titlepages.html and 

http://www.sagehill.net/docbookxsl/HTMLTitlePage.html

I think I understand the broad outline, but there are a couple of things that I may not understand yet.

 As I understand it, the bit at the top of the first page of a chapter is considered a titlepage, and the template files allow you to customize it. But I don't see any reference to the chapter label, either in the .xml or .xsl template files. For
 example, by default, my chapters begin:

Chapter 5. A Very Important Chapter

but I would like the option of:

Chapter 5 (centered, smallish font size)

A Very Important Chapter (next line, centered, largish font size)

I don't see any way in the templates to refer to the chapter label.

I would also like to control the punctuation at the end of the label, e.g., Chapter 5 (not Chapter 5.), Section 5.2 (not Section 5.2.). I had customized my dsl-jadetex stylesheets to do this, but I can't follow what I did then (years ago) much less translate
 it into xsl-fo.

What is the best way to substitute a graphic for a titlepage element, e.g. the title or corporate logo as separate pdfs or svgs. I'm imagining including a <fo:external-graphic, but I don't see any examples I can mimic.

Finally, I am old fashioned and I like a half-title. The DocCookbook makes reference to this, but doesn't spell it out.

Thanks.