There are buses they have a good system, just ask. You can also take the tram direction Bad Honnef which will get you to the station directly above the area just before crossing the Rhine. Note, the tram is also the Underground!
Just look it up on googlemaps. It gives you all the different public transport options depending on where you want to start and end up. As the Rheinaue is a large area there are more public transport stations you might want to consider.
Yes. A light rail station is there
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