Answer to "iPod Touch 1st Gen. won't restore"To restore any .ipsw file to a device using iTunes, just put the device into Recovery Mode, then hold down the Option key when you click the “Restore” button in iTunes. iTunes will then present a standard File Open dialog, where you can navigate to and select the .ipsw file. iTunes will then restore that file to the device, instead of trying to look for it over the Internet (where it doesn’t exist, which is the issue here).
Answer to "Can we install a second internal disk drive?"FWIW, OWC is about to release a kit that allows 2x SSDs in the Mac Mini 2014+.
Answer to "Mac mini 2015 Dual hard Drive Possible?"Not sure how they're doing it, but OWC is coming out with a kit soon that will allow 2x SSDs inside the 2014/2015 Mac Minis.