Questions about software and batteries - Drone

Hello everybody,

I’m new here and I’m looking to build an open source quadcopter. I want to use a RC controller first, then use the Nvidia TX2 chip for controlling it by Wifi and playing with some scripts.

I’m selecting the different hardware components and I’m asking myself the questions below. Could you please help me ?

  1. When I will install the firmwares inside the Pixhawk and the ESC, do I have to modify the source code for adjusting flight parameters and my hardware ? Or I can just upload it and fly ?

  2. I would like to have a fixed “gimbal” for my camera. Do I have to program the gimbal ? Or without coding it, the gimbal will be fixed and staring at the front of the drone ?

  3. Are the Lithium-Ion batteries (Li-on) reached the point where there are more interesting than the Lithium-ion-polymer (Li-po) batteries ? I know why it wasn’t the case in the past (discharge C rate, weight, safety, price) but I think it’s not the case anymore and I would like to use Fast/Quick charger with Li-on.

Thank you very much for your help.
Have a nice day,