How to aggregate news for an iOS app?

My first post btw :)

Where do I start if I want to write a news aggregator app for an iPhone/iPad? I am familiar with Java but not so much with Objective-C.

So my question(s):

-how do I add RSS and Media RSS (MRSS) to the code in the first place?

-how do I store downloaded news (including media, videos and pics) so it is accessible without wifi/4g once dowloaded? Caching?

-is it legal to aggregate news content from other sources?

-does someone have any links that include some actual coding?

I know how to add RSS in HTML5 but I need help with Objective-c...

Any help and/or links on this subject is much appreciated.

Excelsior!