You can use the EZ* with the ArduMega as well as the Ardupilot and the ArduIMU even thought it does not have ailerons. The rudder will cause it to make a flat turn and generally forces the nose down a little so some up elevator helps.
However, it is not hard to add ailerons to the EZ* wings. I had one set professionally done by Readymaderc.com, but did the other two myself. The professionally done one looks better, but works no better than my own conversions. Also I would suggest adding a bigger rudder. If you search RC Groups, there are plent of EZ* build logs that can help you make the necessary conversions.
Mark , I have flown option1 plenty of times. It was ok for normal flying but is short of space for any thing else other than the basics. you need to do some mod or loose the canopy if you need to get your Mega on it decently.
option 2 ,not tried but looks it will be short of space too for our needs.
Try option 3 ; Skywalker. I haven't flown it yet but you won't have trouble with space at all for all your goodies. I don't have any complains so far building it. :)
I've read a few stores on them breaking. This will be first RC plane. I want to learn and practice flying it first without the autopilot and then install the autopilot. I'll try to choose between the Easy Star and the Skywalker. For a first timer, do you think the skywalker is a good idea?
I should add, the plane is also very quick and easy to build, although it comes with no instructions, none are really needed.
You will also want to reinforce the wings with carbon. There is a thread on rcgroups about this.