Translation:The convenience store is over there.
こちら = Over here/this way (near the speaker)
そちら = There/that way (in the listeners direction)
あちら = Over there/that way (away from both the speaker and the listener)
どちら = Which way (question word)
What's the difference between Koko/Soko/Asoko; Kochi/Sochi/Achi; and Kochira/Sochira/Achira?
from what i understand, it's level of politeness. from most casual to most polite, it goes こっち --> ここ --> こちら.
Is there a reason that "A convenience store" doesn't work? (Instead of "the")
Just because that answer is not in their database. If you report it thay will probably add it
Different definition, based on how Duo works. "A" wouldn't be as precise as "the". They both refer to one thing, but "the" infers that it's more important/the speaker knows which one they are talking about.