Great questions on the Citabria.
Yes, I use two 3200 mah Hobbico LiFe batteries. They wind up being just about exactly under the CG. I am not using a choke servo. I always run a pushrod through an aluminum bracket that I make, which is captured by the two mounting bolts on the left side of the engine. The end of the rod ends up right in the middle of the left side cowl air intake. I attach a wheel-collar so that you can easily push in the choke rod to choke and pull out to turn off the choke.
As for a prop, I use Xoar props on all of my gassers. On this one, I have an 18X8. I also use 18X6 props on the DLE 30's, if you end up with a little too much residual thrust at idle. You'll get a few more revs at full throttle, but you get a little more drag and it's a little easier to slow down on final. I'll attach a few photos of the airplane here, then add a few more of the interior details later this week. I didn't add the cockpit floor just yet, wanting to make sure I didn't have to make any changes after the first few shakedown flights.
I mounted a "Miracle" switch (two switches mounted in an aluminum housing for receiver and ignition) on the right side of the fuel tank, where you could mount a couple of servos for the throttle and choke. I also mounted the ignition LED right next to it and the optical ignition switch as well.