I’m a Mac / Linux user too and the device not showing up as a mass storage device is certainly annoying as it doesn’t allow the integration with Calibre that it should.
I have captured a USB debug output with the device connected and opened a bug with apple (not sure what this will achieve if anything but I figured I’d do it anyway).
I also contacted the Calibre author, he said he can add new devices to the software but only if they show up as mass storage devices. I told him I’d run the debug from within the application under windows so that he can get the device ID and write a driver for it so at least it will work under windows once I’ve managed to get him the info.
In the meantime I’ll try to discover why it shows up on windows ok but not mac / linux. If I have any joy I’ll post here.
Oh, and with regard to the search being useless, it’s not useless, it’s just poorly documented how it works. If you do a search for book title in your library the first two spaces are taken up by the search box. Basically if you press the number 3 it will jump to and open the first book title it finds that matches, 4 would be the second match etc. It’s quirky I know and it’s probably because the interface was designed for a touchscreen but it does still work, with text search within documents you just use the arrows to navigate from what I remember.
Hope this helps!