I applied online. The process took 2 months. I interviewed at US Army (Fort Lewis, WA) in May 2012
Interview
All job applications are accepted only through USJobs.Gov now. I was working overseas and was told by email I had 3 days to accept the position or I could decline. So technically I did not even interview for the job. However, that is not the norm, most interviews are done over the phone for initial contact. Even then a manager can hire you outright if your resume is strong and you have hiring points (Vet, Spousal Pref, Disabilty). Most likely they will want to have you come in for a second interview unless it is in a geographically distant place. From my experience, you are more likely to get hired if the job requires relocating. Note: many Government jobs are open to local commute only.
Interview questions [1]
Question 1
Most Government position are locked in a certain paygrade and step, so you know what you are getting before the interview. Once you factor in locality pay for the job, you pretty much know what you are getting. However for new hires or certain jobs such as Medical and Senior Executive Services, there are bonuses and pay negoiating. The hardest thing is knowing what the agency is WILLING to pay and what you want to be paid.