As a general rule, the horizon should be level. Depending on the angle of view, the bridge may or may not appear level, but if the horizon is level, the bridge will be convincing.
Unless, of course, you want it to be unconvincing.
I don't photograph subjects, so I'm not able to offer a suggestion there.
As for the foreground, again the general rule is that whatever is there should be in focus. Unless you don't want it to be.