Any scanner will do provided it can scan transparencies as well as photographs. I have not run Linux since the days of the very early Red Hat distributions. I cannot help with scanning software. In the non-Linux world I would suggest something professional in the way of scanning software such as Silverfast. Vuescan is also an excellent piece of software and version 9.4.32 should run in Ubuntu.

Look here: http://sysads.co.uk/2014/05/install-vuescan-9-4-32-ubuntu-linux-mint/

You should find a list of supported scanners and you can pick the best of them by looking at their native resolution and whether or not they provide a transparency scanner hood with the device.

In terms of scanning resolution you will not need more than 300ppi if you want to print the photographic images at their original size and web display will not require more than 100ppi. Save the files in a format that will be transferable and useable later. Avoid .jpg files because each save will destroy a little more of the file and they will deteriorate beyond useable after several saves.

Suggest a scanner which can scan natively up to 2400 ppi. More is nice but it creates enormous files which you do not need. Another storage format you may consider is PNG. Alpha channel (transparent) support and lossless 16bit files are possible. Does not support CMYK so file printing can be problematic.

My preference would be to save files with as much information as possible so that would probably mean a lossless file format such as .tif and a 16bit file format so that reworking of the file would be as painless as possible. It would mean more file storage space is used though LZW compression is available. Consider a scanner which can save RAW file format because there would be no loss of information and the opportunity to rework the file would always exist.

As for RAID, I suspect it is far better to avoid it. If you use a single disk, its failure is less likely than if you use multiple disks because you are effectively increasing the risk of failure with every disk added to the storage solution. I would opt for a single disk, copy it and store the copy off site. I once had used a very large and expensive tape drive of 20GiB capacity. It was slow, sequential and when it failed, I was unable to retrieve any of my data.

I forgot to add that most of your file transfer post scanning in Linux would probably be via the GIMP software (the Photoshop simulacrum). I have not used that for 10 years and the last time I looked it could not use or process 16bit files. That may have changed but it is worth bearing in mind if you are going to keep the maximum detail in your scanned images.

Hope this helps