you dont have to set a password for root, you can just so sudo su and use your username password and it will enter the root shell
on building bfgminer post the errors, but it looks like you missed ./configure after ./autogen.sh
was it this when running ./autogen.sh
Running autoreconf -if...
./autogen.sh: 17: ./autogen.sh: autoreconf: not found
If so install autoconf and the other dependenices
remove the sudo if you have already used the su command.
sudo apt-get install autoconf
sudo apt-get install automake
sudo apt-get install libtool
sudo apt-get install pkg-config
sudo apt-get install libcurl4-gnutls-dev
sudo apt-get install libjansson-dev
sudo apt-get install libusb-1.0-0
sudo apt-get install libusb-1.0-0-dev
then
./autogen.sh
./configure
make
once its compiled with no errors
edit: had wrong libusb package
output should look something like this for ./configure
Avalon.ASICs.........: Disabled
BitForce.devices.....: Enabled
Icarus.FPGAs.........: Enabled
ModMiner.FPGAs.......: Enabled
X6500.FPGAs..........: Enabled
ZTEX.FPGAs...........: Enabled