Torah study

Shalom Aleichem Rabbi.
Do you have any questions?
1. Is there a commandment to study Torah when one does not speak out but thinks in one's head? I am not clear on the matter.
2. When I study in my mind, I am able to meditate for much longer.

3. When studying Torah for a purpose, such as a philosophical book for a Torah matter, is it not appropriate to utter the words in order for it to be considered Talmud Tanra? I assume, what does the Rabbi say?
In general, isn't the idea of ​​putting it out in the mouth only about learning the five books?

Thank you very much.
Good afternoon