Questions & Answers about Den där mannen går med käpp.
Why is it Den där mannen instead of just Den där man?
In Swedish, when you use the demonstrative words den där (that) or den här (this), the noun that follows must take the definite form. Even though we just say "that man" in English, Swedish literally says "that there the-man".
Why is there no en before käpp? English uses "with a cane".
Swedish often drops the indefinite article (en or ett) after prepositions when talking about tools, modes of transport, or instruments used for a general purpose. Just like you say åka bil (go by car) instead of åka en bil, you say gå med käpp to describe the general act of using a cane to walk.
Since går can also mean "goes", could I use promenerar to be clearer that he is walking?
Not in this context. Promenerar specifically means taking a leisurely walk or a stroll for pleasure. Går is the correct verb here because it refers to the basic physical act of walking on foot, which is what the man needs the cane to do.
How would this sentence change if I wanted to say "This man" instead of "That man"?
You would simply change Den där (that) to Den här (this). The rest of the sentence stays exactly the same, keeping the definite noun: Den här mannen går med käpp.