You can use the one that starts from bc1q or bc1p to donate bitcoin.
2.
Sometimes in the future I will be required to show simple Bitcoin tasks to an audience. That means a transaction (of about 5 USD) to a
person of the audience should be confirmed withhin about 5-10 minutes. Should i use Bech32m (Taproot) addresses for such a demo?
You can use any if the two but make sure you use fee rate of high priority. You can check the mempool to know the fee rate that you should use.