Translation:Please stop at the corner.
Don't think of は as the subject necessarily. It may be easier to think of it as the general topic marker.
The topic of this conversation is the かど. Even though で is used to indicate where the action is taking place (at the corner), it is still the topic of discussion so we add the は. As in yes the action is located on the corner (hence で), but our topic is also that corner (hence は).
That is how I understand the role of は- as the topic marker. So any time you bring up a new topic, you usually introduce it with は.
Unfortunately no. The は's only role is to mark a newly introduced topic. It doesn't tell the listener where the action took place. That's is the role of で in this case. If you were going TO the corner for example, it would be には. As in, yes the corner is the topic (は is used) but に indicates some directionality of action (like we are going TO the corner, which is now the topic of the conversation)
Again, another case of kana-only sentences making it much harder to read than if kanji had been used...
The verb is not まつ (待つ) "wait" but rather とまる (止まる) "stop".
Those verbs in て-form:
- まつ → まって
- とまる → とまって
Here's how that sentence would look if kanji were used:
A「かどではとまってください。」 indicates what should be done at corners in general: stopping. "Please stop at corners."
B「かどでとまってください。」 indicates both (1) what should be done and (2) where: (1) stopping, (2) at the corner. "Please stop at the corner."
It is unnatural to translate A as "Please stop at the corner."