Haha, I'm a total newbie too and I don't know what to practice so I just try to memorize scales, the notes on fretboard, songs that I find easy or a bit of challenge to me. =] (I'm a bassist so I skipped chords lol. =X )
Maybe try 21 guns by green day?
That's the first song my brother's friend learn when he's a beginner.
As for the speed, if you can't catch up, play it slow first and get used to the chords that you have to play.
You know, after a while you might feel that practicing is boring.
I'm sure many people feels the same too, haha.
I usually motivate myself by telling myself that 'Hey, I've actually improve since when I've just started and don't know anything. At least I have improved abit, and not nothing at all.' =]