»Live CD for removing malware?
»Best free bootable antivirus for usb stick?
2. yes, most of the time, but it is always better to check with a couple of different programs
If you have a locked down computer spare with an A/V, using the infected HDD as a slave and scanning will also work.
3. See point 1 and also this »Security Cleanup FAQ »Rootkit Detection Applications
Note: if anything is detected, to be safe, visit »Security Cleanup
The only thing necessary for the triumph of evil is for good men to do nothing - Edmund Burke