Is there anything I can do about a teacher who is rumored to be unreasonably severe and whose class I am about to take?
As a former college instructor myself, the number one thing that made me willing to work with students was a willingness on their part to form a mutual relationship of trust. 

I was always much more willing and desirous to help a student out when they treated me respectfully and did not treat me like I was out to ruin their life.

Let me also add that it is always of benefit for the instructor to know who you are. This is especially true in a class that potentially could have 50+ students in it (like introductory English). Try to find a way to introduce yourself to the instructor by asking a meaningful and intelligent question after the first class. Even just introducing yourself can sometimes be of benefit. 

In closing, may I also be generally blunt? College is an entirely different beast than high school. The standards are often much higher. The negative reviews of this teacher could be negative in part because he is handed a sloppy bunch of kids who just want an easy A. Not always is this the case, but it is sometimes the case.