It seems like much of your outputs are digital servo pwm signals. I guess the intent is to have your board power an ESC? ESC's for all the functions such as turret traverse, elevations, smoker, etc. Plus the board for under $100?

It's an ambitious project for sure and the Arduino is up to it. What are you proposing, a battle circuit or an entirely new tank electronics package? Open source is good but it looks like you are trying to design a system for your tanks for your needs which kinda kills the open source allure. Maybe you could back track a bit for us and tell us the scope of what you are trying to do. Why will this be better than El Mod? Cheaper? It is looking like it might not be.

It's a good project and a noble cause but maybe if you put a survey out to the forum members as to what they are looking for it might be more 'universal'

Perry