Ehhh ? ;-)
Looks like you're looking at some rather heavy Android App development
beyond 'parameters' and 'formats' from Elgg.
Elgg is basically Browser (PHP,etc) based..
And does not know what the Android OS is ;(

Moved to plugin development group as that's a better place for this discussion

1. You can create a mobile theme so that members on a mobile device can use the site like everyone else

2. You can create an app for your site. Elgg provides a web services API that lets you expose functionality by writing a plugin. You would then write an app that uses the methods that you exposed in Elgg. There is more information on the web services API in the Elgg docs: http://docs.elgg.org/