If you are angry, stop using particles. The sudden lack of 'khrap' or 'na' signals to a Thai person that you are serious or upset without you having to raise your voice.
It can be. In formal settings, it's safer to use 'Phom' or 'Dichan' or your title. However, once the conversation is flowing, you can drop it to avoid sounding repetitive.
You don't! Thai pronouns are gender-neutral. You have to know who you're talking about from the previous sentences.
It's not 'wrong', but using it in every sentence makes you sound like you're reading from a textbook. In casual conversation, it can feel stiff.
Look at the context. If you just gave someone something, it's 'Thank you/You're welcome'. If they offered you something first, it's 'No thank you'.
In Thai, เขา is gender-neutral. To disambiguate, you can add ผู้ชาย (man) or ผู้หญิง (woman), or use their name/title.
When counting or specifying ('this/that'), yes. Skipping it makes the sentence sound broken or ambiguous.
