"Do you know where the gallery is? It is up ahead."
Translation:Ты знаешь, где галерея? Она впереди.
No, since you've already specified that you're talking about "галерея" or whatever, you have to refer to it with personal pronouns он, она (here), оно. Although in colloquial speech "это" can be used, but basically it sounds awkward.
So это is used when you have not defined the thing you're referring to, but if you do know what it is, you use the pronouns он, она и они?
E.g. if you ask with the indefinite pronoun "это", you can be answered with it as well: "Где это находится? Это находится впереди". All in all, он/она/оно reflect something particular and you mentioned it, you or your listener can replace them with the particular subject. Это is usually when you can't, when you haven't mentioned the thing or it cannot be mentioned (e.g. it was a description or a verb, you can't address a description or a verb with personal pronouns, or the object of the word is banned, or there is no term yet for this in human language).
Yes. Usually "вперё́д" is used with a direction of movement, and "впереди́" with a location of an object.
We have to go forward because our goal is up ahead
Мы должны идти вперёд, потому что наша цель впереди.
Thank you. Russian has a lot of distinction about location and motion. It is nice and awful at the same time.
Is the reason you use 'Она' instead of 'Оно' here due to 'галерея' being feminine? Just wondering because I thought you would always use 'Оно' for 'it'.
Is there exist the difference between «it is ahead» and «it is up ahead»? These two phrases have the same meaning?
My guess is "up ahead" is somehow closer than "ahead", which is more vague... Like, "up ahead" is something similar to "right in front of you" and "ahead" is "somewhere in that direction", if it makes sense...
No, it is not wrong:
Ты знаешь, где галерея находится?
Ты знаешь, где находится галерея?
P.S. These both are correct, but the second one is more native.