You can get the source code here --> http://httpd.apache.org/
when you configure a suitable configure line should be
./configure --prefix=/usr/local/apache --enable-so --enable-cgi --enable-info --enable-rewrite --enable-speling --enable-usertrack --enable-deflate --enable-ssl --enable-mime-magic --enable-vhost-alias --enable-dav-fs --enable-dav
some of these options may not be needed but this should give a robust and scalable webserver that you dont have to recompile later because somethings missing.
NOTE: I would uninstall your apache rpm before installing the new apache, if nothing else just for the sake of confusion.
I would suggest going with apache 2.0.52 and then compile php 4.3.9 afterwards. this will give you the latest builds on both.
you can get php from http://php.net
I would not suggest using php5 yet.
configure line for php would be something like
./configure --with-apxs2=/usr/local/apache/bin/apxs --with-mysql --prefix=/usr/local/apache/php --with-config-file-path=/usr/local/apache/php --enable-force-cgi-redirect --disable-cgi --with-zlib --with-gettext --with-gdbm
theres a great tutorial on this at http://dan.drydog.com/apache2php.html
notice the tutorial does not compile webdav in though, use the configure line i gave you.
More questions? post again
Hope this helps,