As do members of unions and members of activist groups. Using your logic these groups of individuals should also be silenced.
I agree. No additional rights because you have pooled your money.
As the court has said, a group of people have the same speech rights as individual persons. There are no additional rights, just the same right.
Except, corporations are allowed to participate in elections to an extent and in ways that private citizens cannot.
Using your logic employees may have even more rights than shareholders. In your logic shareholders may have two voices, individual and corporate; while employees may have three voices, individual, corporate and union. Again I am referring to a situation such as "a steel corporation wanting the government to maintain a tariff on steel imports". The steel workers union would probably want the government to maintain the tariff too.
Right. Everybody gets the same vote. Everybody gets the same campaign finance limit (and citizens only). That's simple. Corporations, unions, etc are not citizens. They cannot vote or run for office. Why should they be allowed to participate in politics financially?
And if it was all about "rights" why has Citizens United allowed corporate donors anonymity in political finance when individuals are not allowed to be anonymous in the same way?
You make the mistake of thinking that everyone who disagrees with you is a liberal. You have an image living in your head that is not real.