How to tell what model is currently used? How to specify a model?

I have a few issues/difficulties with selecting different models

Is there no way to tell what model the package is currently using for previous prompts or current selection?
I know we can list listModels models, but when setting a modelName in the chat, I have no idea of the selection is applied and it uses my specified model
What format do I need to specify models. E.g. the listModels returns model/gemini-2.5-flash-preview-05-20, do I need to include the "model/" prefix ot only the model name gemini-2.5-flash-preview-05-20?
What is the default model this package uses?

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