In Eclipse, can I remove the red error markers?
It's possible to tell Eclipse not to underline the text / show it in the vertical or overview ruler by unchecking all checkboxes in Window -> Preferences -> General -> Editors -> Text Editors -> Annotations -> Errors
As you only want to view the code, I'd recommend another editor like Notepad++, Sublime Text or (my personal favourite) vim/gvim. Eclipse is a little bit too 'heavy' for just viewing code.
If you are using the CDT plugin, which you probably are as you're using Eclipse for a C/C++ project:
Window
->Preferences
->C/C++
->Code Analysis
.- Disable Potential Programming Problems and Syntax and Semantic Errors.