Before you trust your photos to a scanner, maybe you should check it, scanners from all-in-one printer/scanners are mostly designed to scan documents, color fidelity may not be their top characteristic. Some also introduce transversal distortion, are slightly misaligned, or do not scan to the very edge of the scanner bed. All this can be checked by scanning squared paper with a few arrows drawn to the edges, carefully tucking the sheet along the side of the scanner bed. You can then check:

• That you see the tips of the arrows
• That the vertical lines are indeed vertical in your image editor
• That the intervals between the first vertical line and the others follow a linear progression. No home-grade scanner is perfect, so expect to find slight inaccuracies, that won't really matter. But this can also reveal some more problematic ones.

Then:

• Scanning at 600DPI will produce decent 8Mpix images, good for most purposes.
• Usually one tucks a size of the photo along a side of the scanner bed. But you can discover that your scanner is slightly misaligned that way (something scanning squared paper will also show).
• Cropping is better/cleaner even if the un-cropped bits are likely to be very easily compressed and not add that much to file size. I advocate cropping because it makes you look at the scanner output when you can still fix things (misalignment, etc...)
• Image file format:
  • TIFF is OK, but if you use JPEG compression in the TIFF you have to be able to control the compression/quality level). Using high-bit depth (16-bit or more) is likely overkill given your scanner.
  • JPEG is adequate at good quality levels (90-95). At 8Mpix your image files should be about 2MB, if they are below this you are possibly compressing too much.
  • PNG is lossless but the compression algorithm is slow, and won't find much to compress in a photo.
  • File size shouldn't be a concern given the size of mass storage these days, unless you save to the cloud and you have a slow link.
• Storage:
  • You can use the cloud as a secondary backup, but don't put too much trust in it. Unless you pay a dear price you'll discover that the provider doesn't feel too concerned about the safety of your data. Also, writing is cheap, reading back can be expensive.
  • Ideally you want at least two media, not kept in the same physical location (leave one with a parent/friend, or in your office)
  • The most reliable long term storage is the old-fashioned hard-disk.