The problem in #1 is that the scene is backlighted. That tends to make the subject silhouetted. There's not really much you can do to fix that. Next time, go for a time of day when the sun is in your favor.
The red lighthouse looks like it was simply rendered too dark, but Mike fixed it up fine.
The twilight scene is excellent - just enough detail in the foreground rocks to allow them to contribute to the interest. Very good exposure and excellent composition.
The flower picture has great depth, excellent lighting and exposure - too bad the end of the pistil was cropped off.