1) This works only for new clients.
2) apache always runs under the apache user. But thats not a problem at all asll all repos can be owned by the apache user as the login permissions were handled in the svn-passwd
and do not depend on the file permissions and /path/top/his/home/repos
can be anywere on your server and has not to be in the home directory of the user as the user is able to access the repository by webdav and does not has to access the files directly.