Am I being exploited by my supervisor? It has been 4.5 years since I joined as a PhD student. 


My supervisor asks me to draft almost all of his important emails. He will begin by briefing me the issue, and ask me to draft the email in a document and sent to him. He would ask me to do this even when I am busy doing experiments. Many times I have to leave the experiment in the middle to draft his emails.
He has asked me to correct PhD thesis of three of my seniors. I was asked to correct the thesis for language and technical content. These assignments put me months behind my planned schedule. I guess correcting a thesis for one of the senior would have given me a learning opportunity on how to write a good thesis, editing, formatting, etc. Three theses are, in my opinion, too much. I don't know why he never assigns such works to other students in the research group. 
One day he shared some experimental results of another PhD student (who is a junior to me) and asked me to perform statistical analysis on the results and draft a research manuscript. It took me days to complete the analysis and write the manuscript from the scratch. When it was finally ready for submission, I requested him to keep the author sequence as: my junior (first author), me (second author), supervisor (third author). On hearing this he became extremely furious (he keeps himself as the second author in all the research papers), and indirectly warned me that he won't be taking interest in supervising my research. Fearing that my work progress could go haywire, I apologized profusely and I had to literally 'beg' him to forgive me. I made the request for the author sequence because I have seen that professors usually keep the names of students earlier in the author sequence before their own.
I have been devoting 1.5 hours every weekday (Mon to Fri) to tutor his daughter in high-school Mathematics. That takes a precious amount of my time which I'd have instead spent on my research. I politely expressed that this work takes a lot of my time, but he still asked me to continue. I had no choice but to continue. 


What I would like to ask here is am I being exploited/abused, or is this what  a PhD student is 'normally' expected to do? How is the PhD student and supervisor relationship ideally supposed to be? Since the PhD degree is extremely important for my career, I have been doing everything he has asked. But I don't really want to be a supervisor like him in the future when I will be supervising students working with me. Please share some advice. 

Update: The region is South-East Asia.
Yes you are.

Point 4 is downright abuse of power. You are not in any way obliged to provide free tuition to your advisor’s child! If your institution has reasonable management, you reporting this would result in severe disciplinary action (I think I would have my tenure clock pushed and have something on my record for something like this). Even if you were paid to do it I’d feel weird about having my students tutoring my kids. Depending on where you are on the planet, not getting paid for tutoring is illegal. Your advisor would be in serious legal trouble if you are in, say, the US or Europe.

Drafting emails seems like an odd practice. It’s abusing power to some extent but if the emails are relevant to your work it might be construed as acceptable by some department heads. That said, you’re a student, not a personal assistant, seems like a waste of your time. 

You should not be reading and correcting others' work with no credit, this is the advisor’s job. I would be upset if I were the one of the students who didn’t get their advisor’s feedback! 

Being an ass about authorship is another bad sign, though in itself may not be too bad. Disagreements about authorship do occur, though the response you describe seems wildly disproportionate. Getting students to the point where they have to 'beg' for your forgiveness is never okay. His job as an advisor is to educate, teach and advise - you are not his pawn or slave. 

Taken together, what you’re describing is a toxic and abusive relationship. 

What you can do depends on where you are in the world and your department. Most reasonable universities have ombudspersons or student support centers whose job is to help people in your situation. If no such thing exists you can try to approach your department head or dean. 

You need to have clear-cut evidence. Emails, records of your visits to tutor the advisor’s kids, written proof that you corrected the thesis of others (say, an email exchange, files sent to you with request for correction, or any other acknowledgement) etc.

I’m sorry you’re in this situation, hope you get things settled. The tone of your post does not make it sound like you are in severe emotional distress, but of course it's impossible to tell. Make sure you get emotional support through what is undoubtedly a rough experience. You do not deserve this, and you should not feel like this is normal.