Caching for *.wikkii.net sites

If any reader can fill in the blanks below please respond.

Refer also: http://www.mediawiki.org/wiki/Manual:Cache and subsequent links.

PHP caching
It seems clear from this notice that follows a MediaWiki installation that there is no provision for PHP caching.

Quote

Couldn't find eAccelerator, APC or XCache; cannot use these for object caching.

Object caching
Is memcached an option at *.wikkii.net sites and if so, then are the configuration tweaks shown below appropriate?
default:

Code:

## Shared memory settings
$wgMainCacheType = CACHE_NONE;
$wgMemCachedServers = array();

MW proposed:

Code:

$wgMainCacheType = CACHE_MEMCACHED;
$wgParserCacheType = CACHE_MEMCACHED; # optional
$wgMessageCacheType = CACHE_MEMCACHED; # optional
$wgMemCachedServers = array( "127.0.0.1:11000" );

$wgSessionsInMemcached = true; # optional

For lack of better information about what processes (daemons) are running on the server, I have left object caching set to none.

Localization caching
Relevant only to MediaWiki 1.16.x, it isn't obvious to me how this differs from page caching (see File cache, below).
The default setting of $wgFileCacheDirectory is "false" but a prompt is there to specify "$IP/cache" as a local cache. The instructions state that, "this directory should be made writable but not accessible from the web." Am I to understand this to mean 700 permissions on that directory?
... or 770 or 777 ? (The default permissions are 755.)

File cache
Ok so this piece was straight forward - following the directions at Manual:File Cache

Code:

$wgUseFileCache = true; /* default: false */
$wgFileCacheDirectory = "$IP/cache";
$wgShowIPinHeader = false;