You seem to have pretty much covered everything that is needed. As for target language, you express it well yourself: "how to give, ask for, and understand directions".
I suggest you adapt some of the language; I would keep the questions simple for a number of reasons:
the language of directions is not easy and students will need time to master (or mistress) it. So go easy where you can.
Also, and I know this from personal experience of learning German, it's very easy to ask the question "where's the post office?" but it's a lot more difficult to understand the answer. I think your focus in the lesson should be on the directions and not the questions.
I suggest you cover just 2 questions:
Can you tell me where the *** is?
Where is the *** please?
As for the language of giving directions:
the following are essential:
It's next to the ***
It's across from ***
It's on the corner of *** and ***
It's on *** Street/Road/Avenue
It's opposite the ***
Turn left on ***
Turn right on ***
Go N/S/E/W on the ***
the following can be taught depending on the material you are using to practise the language (ie, if students will need to say these things):
It's at ***
It's in the ***
It's just past ****
I suggest you leave out the following;
It's that way.
Go down *** to ***
Finally, I suggest you revise briefly at the beginning of the lesson prepositions of place and locations in the town just to check to what extent students know this language.