Question about USRP E100 Device

GNU Radio
1

  1. 4GB microSD Card already has ubuntu or other OS installed? Where I
    can download prebuild image?

  2. UHD, Gnuradio and Linux OS are prebuild and installed at SD Card?

  3. E100 support multi-thread application?

  4. Since E100 no hard driver, can I use USB external hard driver log
    data?

  5. When Gnuradio need do FFT, are we use TI DSP chip or just ARM chip?

Thanks