Explain how money is speech.
Money is not speech. Money is money, and speech is speech. It costs money to broadcast speech.
Show how government by the highest bidder is appropriate.
It's not appropriate. But that's not what Citizens United did.
Tell why a coporation is a person.
A corporation is not a person, a corporation is a corporation and a person is a person. Corporations are comprised of people.
Pretend you are on a debate forum, where facts are proven by proof, not your say so alone.
Wow... that's going to be tough to do in this thread, where "facts" are hyperbole and "proof" is rhetoric, and you have no intention of honest debate.
Show why the first ammendment protects the spending of multi-national companies, and why centuries of limited campaign donations was wrong.
I think you are either confused or misinformed about what Citizens did. First of all, Citizens was not a "multi-national" company, it is solely a US company. Second, we still have limits on campaign donations. In 2002, we passed McCain-Feingold Campaign Finance Reform, which restricted what Citizens did. In 2010, the Supreme Court ruled this unconstitutional. Before 2002 and after 2010, what Citizens did is perfectly legal and doesn't violate any campaign finance law. From 2002 to 2010, their first amendment rights were being violated by McCain-Feingold, or so the SCOTUS ruled.
Finaly, explain how representative democracy is enhanced by billions of dollars of untrackable donations.
It's not, and that has never been the argument. You know who Citizens is, don't you? Seems like that point alone would prove they aren't "untrackable." And what they did, was not "donate billions" but rather, produce a product for distribution to the public. It so happened, the product was political in nature, and fell under the description of "political advertising" covered in McCain-Feingold. The court ruled, under the first amendment, the company had a right to free speech, and this could not be restricted by campaign finance laws, because it is an inalienable right.