Roughly 70% of body composition is what you eat, you cannot out train a bad diet. There are no bad foods, it's the dose that kills you.
Apart from B-12 most vitamins don't give you energy, they fill a slot to perform a needed role and are flushed out regularly-thus needing to be replaced.
In general: cardio takes weight off, resistance training puts muscle on, endurance gives you stamina for the level of strength you want to develop.
Walking counts as exercise, after 30 minutes you stop burning sugar and your body breaks down fat. Anything you add on top of this reduces this time frame.
Older reports held that an 8MPH run would boost metablolism 13.5 times normal, swimming burns more calories than running-and also has the least impact on joints, and 90 minutes of cycling at a moderate pace would burn 1000 Calories. These findings may have been refined since then.