Starter

This is the first time I have ever owned or even worked on a diesel and I have
no idea where to even start with it. First off what would cause my antifreeze cap
to keep blowing off while I am driving, also what would cause white smoke
instead of black out of my exhaust, and last what would be the cause of my
starter going out? This has all happened in just a a few weeks a part from each
other. If I need to get into more detail please just say so in your response and I
will. Thank you.