Just fyi, you are likely to get more active responses from me via LinkedIn.

* You can refer the material they give you. It will be open while you present. However, simply reading from it won't work in your favour. Imagine a real teaching scenario ... you will be expected to know the subject and talk about it while using the slides as a memory jogger. So, the evaluation also checks you on that.
* I'm assuming that if you have been working towards the GCP Authorised Trainer, you have access to a GCP account somewhere. That should be good enough. The evaluators are not going to ask you to create a huge project. Only to do basic tasks around the console. If I remember right, they don't give you any credits or a specific account.