There are various rules on what is and is not acceptable to drink. While you would most often be drinking champagne or some other form of sparkling wine. If you do not it is acceptable to drink sparkling fruit juices or water. You should however always at least take a drink of something. To have a dry glass is considered rude in most societies.
It is considered impolite for the person being toasted to rise while the toast is taking place. Typically the one being toasted also does not take a drink. They should however after all toasts have been given rise and give a formal thank you to all whom toasted them.
The part regarded as the actual toast is typically a small and possibly sing songy verse wishing the couple happiness. An example would be:
May the road rise to meet you.
May the wind be always at your back.
May the sun shine warm upon your face.
And rains fall soft upon your fields.
And until we meet again,
May God hold you in the hollow of His hand.
-Adaptation of an Irish Toast
Read: Part 1 | Part 2