Replacing faulty MultiWii with APM 2.6 on ARF kit

Hi everyone,

I have bought following arf kit from China:
http://www.aliexpress.com/item/RC-FPV-RTF-Drone-Quadcopter-FPV-Kit-Flamewheel-Landing-Gear-KK2-5-Controller-OSD-Motor-ESC/32320628148.html

And after assembling everything I found out that either MultiWii controller or FTDI/USB connector was faulty and I simply can’t access it from my computer.

First, I thought about buying another MultiWii controller, but then I’ve found out that APM 2.6 has bigger user base, is more customizable and so on and so on. So now I’m thinking about buying APM 2.6 and installing it instead of MultiWii controller on above ARF kit.

Please note that this is my first quadcopter assembly and I’m interested in getting quadcopter simply fly manually without GPS and other bells and whistles. After that I’m interested in altering the code, attaching sonar sensors to this quadcopter and experimenting with it. So in the long run I’m more interested in coding rather than setting everything up from UI.

After reading articles on the web I found out that there could be 2 issues with such replacement:

  1. APM 2.6 comes without magnetometer (which is present on MultiWii). However after reading resources on the web I found out that quad could actually fly without compass (magnetometer) if no fancy modes are needed - please advise
  2. Obviously, APM 2.6 needs different power supply than MultiWii, so I wonder if battery, ESCs and motors from my ARF kit will match with APM 2.6 in terms of power supply? Or do I need to buy another BECs or anything else? Basically for now I’m interested in getting it to fly as soon as possible, so I’m not very eager to search & buy anything else
  3. Please advise if you think there may be other issues when replacing MultiWii with APM 2.6 in my ARF kit and if I need to buy anything else

Thanks in advance for any help and hints!