Using Real-Time OpenAI Models in AI Agent API + Issue with Free Version

Hi everyone,

I'm exploring D-ID's AI Agents API and noticed that the service uses ChatGPT models for natural language processing. I have a few questions, and I'd appreciate any insights:

Is it possible to use OpenAI's real-time models for both text and voice input/output? (For example, to get faster voice responses or have Responses in other languages.)
The AI Agent I created in the free version is not functioning correctly. Is this due to free account limitations, or could there be another issue?
If I use the paid API, will the D-ID watermark still appear on the avatar image?
If anyone has experience with this, I'd appreciate your help. Thanks in advance! 🙏