Is the story of the dead monitor lizard that spoke at the hand of the Messenger of Allah, may Allah's prayers and peace be upon him, authentic?

This report is incorrect. Al-Bayhaqi mentioned it at length in Dala'il al-Nubuwwah, then pointed out that the responsibility for it lies with Muhammad ibn Ali ibn al-Walid al-Basri. Al-Haythami described him in Majma' al-Zawa'id as one whose hadith is denounced (munkar al-hadith). Al-Dhahabi said in Al-Mizan that this report is false (batil), and Ibn Hajar said in Talkhis al-Habir that its chain of narration is very weak.