The forum font is rather hard to read, specifically in blocks of text. It works fine on single lines, but reading todays patchnotes is unbearable. Is there some way to change this new font? I don't see anything in the preferences/forum options.
Not with in forum tools. You will need to use some sort of browser add on that allows you to make changes to how you view the forum. There is someone around here that has posted one but I can't recall exactly. Perhaps that person will show up and fill in the blanks for me.
You need a browser add-on like Stylish, which allows you to define custom CSS styles for a web site. The Feedback: New Forums thread has several custom CSS styles in the first few pages, from which I mix'n'matched the style that I am currently using.