You're correct in needing the ACMT certification. Both exams (Hardware and 10.8, or 10.9 if you wait 4-5 months) are taken online and can be done so without a proctor, someone looking over your shoulder. This changed in mid June when the ACMT certification became a life long certification (no renewals necessary). In the past you would take your initial tests at a testing center or with an approved proctor, this is no longer the case.
All the necessary training is included with the $299 training. With that said, the majority of hardware questions are now very specific in regards to certain models in certain generations. You still have to score almost perfectly in the technician safety and ESD sections but the rest of the test focuses on very specific questions. Stuff like "On the 15 2.53Ghz - which two pins on the logic board do you bridge to power on". All of the answers are in the training available but it's still a tough test to take, even open book, if you haven't been working on these Macs for a while.
With all that out of the way, in order for you to actually put these certifications and skills to use your shop will want to contact Apple about acquiring AASP status. Once Apple deem's your shop to be an AASP then you can actually order parts, perform warranty work, etc. Apple watches the numbers (turn around time, parts used, repeat repairs, customer satisfaction, etc) very closely and has been known to yank the AASP status from shops that consistently fail to meet their expectations. Dealing with them is not fun by any means and I would encourage your shop to reach out to some AASPs outside your region (competitors would just say "don't do it!") for advice on how to get a service side up and running.
Source - I've worked for an AASP for 3 years in both sales and as a technician, as a Mac Genius for almost 3 years and currently am the Mac admin for a very large non-profit organization where I manage 150~ Macs. I'm currently in the process of setting up a SSA (self servicing account) since I still have all of my certifications and it's proving to be quite difficult, though I imagine still a lot easier than getting that AASP status.