For Secondary Socialization, is it guaranteed that you will more likely than not conform to what you experience?
Well Primary Socialization comes first so depending on what happens in your family will usually harden you against things that don't conform to the views of your family but over time or with drastic events in the world around you your opinions and beliefs about things are created based on what you're exposed to. It's not guaranteed you will conform to what your exposed to but the "Media is evil" thing usually helps to ensure you are in some way. It is the job of institutions in society to try and change your points of view about things so unless you can completely block out everything around you then you will in some way conform.
A question for you: can a person change his/her mindset by willpower alone?
You could if you tried really hard, although the easiest way is to just open yourself up to opposing views and ways of seeing things. If you read one particular newspaper then go a week reading one of its rivals instead. If you view someone differently then speak to them and understand them more or live as they do for some time.
Secondary Socialization is affected by what factors in Society you're exposed to. The more things you are exposed to the more your opinions and attitudes will widen and in reverse the less things you're exposed to the narrower your beliefs will be.
This is where your racists fall into. A person is more often than not racist due to their lack of exposure to alternative ways of viewing the people they hate.