I ditto BackPacker's words, just to add something new-ish with regards to US embassy/consulate procedures.
While couple years ago having the specified 2x2in format (times 2) photo was essential, these days it isn't so, at least from my experience earlier this month.
With the advent of digital technology and US govt's agencies doing more 'labour outsourcing to client' a la Ryanair, one has to fill out more and more forms online, now including uploading picture conforming to the criteria. Uploading isn't essential, but strongly suggested and the hard copy 2x2in pictures are more of a backup should visa officers find your digital version isn't good enough for them.
I never had B1/2 visa, nor have I applied for it recently. I just did J1 earlier this month and M1 couple years ago, another J1 in 2003. Chances are, you'd have to fill out DS-1xx form online, with tons of your information, so that they got it all neat without much processing, if with digital format picture, even better for them. In a way, better for applicants, as it may speed up the things.
Basically, it may be another DS-1xx form to fill online, another paper form (not likely as B1/2 visa, since you're not having US sponsor), paying 131 or so dollars plus premium call rate charge for the privilege to have a chat about date and time that is available and suits you all. Then showing up with all the paperwork, without electronic devices, USB drive fobs, mobile phones, PDAs, etc, no big backpacks/suitcase, to get past security.
Depending on the appointment hour - the sooner the better, less of a backlog when only getting in lunch time. Again, depends on individual consulate/embassy. Belfast Consulate is quiet, London embassy busy, etc.
One good thing about B1/2, if you need it, you get the pain done once. It's likely to be for 5 o 10 years. ESTA is now charged, has more limitations, VWP entry cannot be changed to another visa, should you need it. So long you behave and play by the rules, it's good.