When I import and open the downloads I get a .java file with every line flagged with error. This has happened with several projects from the download.

Here is what I have done:
Eclipse works fine with project made from scratch and they are sitting in the workspace seen in the project explorer
I downloaded the files
In the workspace I: Eclipse Menu / File / Import
I point to the project in the download
It imports - no errors
The .java file has every line flagged with error

Yes, this is common.
In Eclipse, choose Window - Preferences - Java - Compiler.
You need to change JDK Compliance level. Try 1.5. You must do this BEFORE you attempt to import any code.

I've had problems recovering after having tried with the "wrong" compliance level. If it happens to you, try deleting the project by right clicking on it and check the box in the dialog (Delete project contents on disk (cannot be undone). Otherwise you risk getting a ghost project which cannot be deleted nor re-imported. In worst case, try importing (with another JDK dompliance level) to another workspace. You can create new under File - Switch workspace. Eclipse restarts itself when switching.

Oh yes, and with the correct JDK compliance, then you can right click on the project in the project explorer and choose Properties - Android. Then you can check the "Project Build Target", for example "Android 2.2". (It is impossible to make any choices there when the JDK compliance level is wrong). You can manage which project build targets are available with the Android SDK Manager, and I think that part is well documented.