Almost everyone who interviews attempts to present themselves, their accomplishments, and their personal objectives politely and submissively to the interviewer.
I hope you are keeping well ....
Hello Dr./Prof. Brain,
I gratefully accept your offer of admission and research assistantship, and I look forward to working with you.
When you write "I hope you are keeping well" or "I gratefully accept," you are subordinating yourself to your "superior."
This attitude is not "academic," it is playing power politics or submitting to colonialism.
The first thing you must do is read everything you can get your hands on your professor has published. Then select any aspect of the professor's writing that jumps up at you. Find something Professor Brain has written, and ask her one or more questions about her assertions. SHE MUST RESPOND--SHE CANNOT HELP BUT RESPOND BECAUSE YOU ARE ACTIVATING THE KEYS TO HER PSYCHE.
When Professor Brain responds, find a term or concept she mentions; and ask Professor Brain to elaborate.
After you have had a continuing conversation with Professor Brain for several e-mail messages back and forth, you can discuss any procedural issues you like. But at that point in the discussion, you will have established where you stand, who you are, and how much you care. Do it properly, and YOU WILL BECOME THE SUPERIOR.