Since various things can cause bad breath, it is difficult to say what you should use.  Watch your diet - certain foods such as onions, garlic, eggs, cabbage, broccoli, etc. can cause bad breath.  When you brush your teeth, don't forget to gently brush your tongue.  And gingivitis and periodontal disease (gum problems) as well as other oral infections can also cause bad breath.  I suggest you see your dentist to determine exactly what is causing your breath to smell.

Finally your question about whiter teeth.  A professional cleaning may help by removing plaque and surface stain.  You could try using a different toothpaste.  While toothpastes don't ``bleach" your teeth, they do remove surface or extrinsic stain, and you may find one that appears to work better for you.  The ``yellow" color may just be the natural color of your teeth, in which case bleaching would help lighten your teeth.  Again, only your dentist can assess your situation and decide if bleaching is appropriate for you.