Thanks for the explanations, 1 & 2 make sense. To be honest, the producing/harvesting mechanic sounds too complicated, personally I'd get rid of it and only produce.
that's the whole point of the game and why/how it go up so not a good idea to get rid of it. But you can explain the mechanic simpler (i think at least) with the cell give number of pieces which control the cell * number of pieces who harvest it which is normally the same. And so the more you control one specific cell the more it produces. thinking with cell by cell seems better than specific pieces i think.