What dpi should I use when scanning photos?

I recently purchased a Epson V700 for its high resolution but I've noticed that the larger the dpi the larger the file (makes sense). My question is actually probably 2 questions. What would be a good dpi setting to set the scanner at? I am scanning photos and am trying to get the best result possible. ... show more I recently purchased a Epson V700 for its high resolution but I've noticed that the larger the dpi the larger the file (makes sense). My question is actually probably 2 questions.

What would be a good dpi setting to set the scanner at? I am scanning photos and am trying to get the best result possible. And should I buy a different program to scan the photos with, like Vuescan or the packaged Epson software going to be good enough?

I really don't know much about scanning photos. I'm just looking to take some 5x7 photos and save them for safe keeping, but I want them to be the best I possibly could get out of this scanner. I just thought of another question.

Should I be saving the scans as JPG, RAW, Tif or what?
Update: Thanks for the tips. I really appreciate your advice. I just have 1 last question. I was using the dpi at 3200 and noticed that even though the picture is clear and the glass looks clean when I zoom in there looks to be lines like a hair line or even dust. I admit I am zooming in ALOT. Is this normal or just... show more Thanks for the tips. I really appreciate your advice. I just have 1 last question. I was using the dpi at 3200 and noticed that even though the picture is clear and the glass looks clean when I zoom in there looks to be lines like a hair line or even dust. I admit I am zooming in ALOT. Is this normal or just need to clean the glass, or is this because I used to high of DPI? After your advice I think I'll use 600 and save it as a jpg and as Raw. (RAW just incase I need to do some work on it later)

If I use 600 will the picture still be clear if we reproduce it at 8.5x11?
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