Should I download delta or combo update for a new MBP with problem?

Hi everyone, my cMBP is a mid 2012 15 iChat version, the screen brightness control and auto graphics switching functions r disappeared by themselves, until recently I heard about combo and delta update, so I hoping this update can solve my problem,

My os x is 10.8.3 out of the box n I haven't do any update yet,

So should I download delta 10.8.3 or 10.8.3 combo?

Will I able to download 10.8.3 delta in the same os x 10.8.3 system?

Should I straight away download combo 10.8.5 update or download 10.8.3 first to prevent problems bring to the new os x version?

Or should I redownload the os x 10.8?

Does this combo update help me?

Btw my mac warranty will expired on mid April

Thanks everyone for helping me!