"For a Federal MP, who writes the speeches in Question Time, Press Conferences, or leadership speeches?"
Thanks for your question. Senators and Members of the House of Representatives usually write the speeches they give. They often work with speechwriters on their staff to write planned speeches to give at press conferences and other occasions.
During Question Time, answers to questions are not written beforehand. However, ministers and their staff members might prepare notes about issues they think they are likely to be asked about.