Docbook 5 DTD questions

[Kate.Wringe@sybase.com]

Hello,

Currently we use Docbook version 4.2. I would like to upgrade to version
5. Unfortunately,our XML editor does not support Relax NG so we have to
continue using a DTD. We also want to upgrade our XSLT stylesheets to 
version 2.0.

My questions are the following:
According to the Docbook V5.0 Transition Guide, if I use the DTD, I should
still "validate my documents against the 
RELAX NG schema before further processing." 

1)I am assuming that further 
processing refers to using the XSLT stylesheets - is this
correct?
2) What is the best way to customize both the Relax NG Schema and 
the DTD? Is it possible to customize the Relax NG schema
and then run a script to create the corresponding DTD?

3)Are there any instructions for customizing the Docbook 5 DTD? The 
instructions in the Transition Guide and the Definitive Guide are
for the Relax NG schema. For example, how can I remove an element?
For example, I've been trying to remove the footnote element using the
following, but this does not appear to work:

<!ELEMENT footnote "IGNORE">
<!ATTLIST footnote "IGNORE">

Thank you,
Kate