
Options Indexes FollowSymLinks↓
Options -Indexes FollowSymLinks他、ServerAdmin などを適切に(適当に?)設定し、/etc/rc.conf に
apache22_enable="YES"を追記してリブートすれば /usr/local/sbin/httpd が起動すると思います。

DavLockDB /var/tmp/apache/DavLock
Alias /dav "/home/dav/"
<Directory /home/dav>
AllowOverride FileInfo AuthConfig Limit Indexes
Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
<Limit GET POST OPTIONS PROPFIND>
Order allow,deny
Allow from all
</Limit>
</Directory>
<Location /dav>
DAV On
Options FollowSymLinks Indexes
AuthType Basic
AuthName "WebDAV"
AuthUserFile /usr/local/etc/apache22/webdav.passwd
<Limit GET PUT POST DELETE PROPFIND PROPPATCH MKCOL COPY MOVE LOCK UNLOCK>
require valid-user
</Limit>
</Location>を追記しました。# mkdir /home/dav
# chown www:www /home/dav
# mkdir /var/tmp/apache
# chown www:www /var/tmp/apache
# htpasswd -c /usr/local/etc/apache22/webdav.passwd username
New password:(パスワードを入力します)
Re-type new password:(再度入力します)
Adding password for user username