I asked this question on math.stackexchange but nobody answers, so I try here even if I'm not sure my question is a research level one..

Let $X$ be a scheme over a number field $k$. Feel free to add any hypothesis you need or to enlarge the setting (for example if there is an answer for any site over $X$). 

Which are the known relations between respectively 

1. The categories of etale smooth sheaves $\mathbb{Sh}_{\text{smooth}}(\text{Et}/X),\mathbb{Sh}_{\text{smooth}}(\text{Et}/X\times\overline{k})$ and $\mathbb{Sh}_{\text{smooth}}(\text{Et}/X\times \mathbb{C})$,

2. The derived categories $D(\mathbb{Sh}_{\text{smooth}}(\text{Et}/X)),D(\mathbb{Sh}_{\text{smooth}}(\text{Et}/X\times\overline{k}))$ and $D(\mathbb{Sh}_{\text{smooth}}(\text{Et}/X\times \mathbb{C}))$,

3. The etale cohomology groups associated with a complex of the previous derived categories.