It looks to me like you haven't set the mpm type USE flag. hence the mpm config error. Just add a line to /etc/portage/package.use and select either worker or prefork.
ex. To use worker mpm: echo "www-servers/apache mpm-worker" >> /etc/portage/package.use
Also be sure to eix apache to see all USE flags available.
ok. well the package that failed for you, built fine for me. (dev-java/icu4j-International Components for Unicode for Java) http://pastebin.ca/718066 I am using 3.4f on AMD64 with nothing extra. you could try looking at what java-check-environment reports, or maybe try getting info from java-config -o or O or L. hope that helps