Translation:Our photos are on the computer.
IN IN IN IN IN the computer.
Sentence uses 里 IN not 上 ON bad translation Duo. FYI they are also called PICTURES ...they would only EXCLUSIVELY be Photos if you used film .... last time I used film was in the last century. Only film photos could be on the computer. Pictures, Photos & Camera Shots can be ON the screen or IN the computer.
I don't think so, as the use of 里 (inside) makes a reference to something being inside the computer, turning the 有 into the verb 'to be' rather than 'to have'. For example, 桌子有一本书 = The table has a book (a nonsensical sentence, I know) but 桌子上有一本书 = There is a book on the table.
For your first sentence, it partially does not make sense, you should say "Our photos are on the computer" instead (taking into sense that the question asked for inside instead of on the computer itself) but regarding your second question it actually does sound more natural if you are using printed photos instead of the ones in documents.
Think of it as seeing the photos on the computer's screen. To our eyes, it looks like the photos are on "the outside" of the computer. You can say "it's on the screen/computer/TV." You can't see "in the computer" - that's where the wires are! (and, yes, where files are stored, which is why "on" and "in" should both be accepted)