Our default state is also the state shown in the preview, it should have gear down, flaps up, engines running, all switches in the cockpit to the flight position (e.g. landing lights, taxi lights off) etc. This is a convention used for multiple reasons, of course you can deviate from this and I want to encourage you to experiment with the tmd file but I'd recommend just wait for us to do this turn around or taxi state for you using a proper new flight configuration like the takeoff or landing config. There are significant changes ahead of us, so all your changes to the tmd files will eventually be overwritten. (so make lots of backups)
Ok, clear, I will wait then. I rather fly than edit files anyway. 
Maybe I should simply skip the entire startup and taxi idea for now when it comes to Aerofly FS 2 and simply start my flights on the runway. (I will go and check now how well that state is or if it needs a lot or work too! )
EDIT
Just had a look at the state as it is when I load the Q400 on the runway. Now of course a few things an be seen as (how do you call it) company policy, but a few I would set differently. The I would personally change:
Engine intake > Closed (instead of Open)
Windshield Heat > Norm (instead of Off)
Panel lighting and Storm > Off (instead of On)
Recirc > On (instead of Off)
Bleed > Off and on Min (instead of Off and Norm)
Weather radar > On (instead of Standby)
MFD2 > NAV (instead of Sys)
That's about it. In can understand some of the choices but imho Recirc should defenitely be on, the Weather radar too (at this point) and the MFD2 should be at NAV at this point. The others are open for discussion or indeed used by some (like a take off with bleeds off). But well, no problem. These are only a few options I have to change before take off.