Let $X$ be a regular, projective flat scheme over $Spec(\mathbb{Z})$, of relative dimension $d$, and look at the $L$-function $L(X, s)$, that is, the Hasse-Weil zeta function completed by the Gamma factors.

Conjecturally, it satisfies a functional equation $$ L(X, s)=\varepsilon(X) A(X)^{-s} L(X, d+1-s) $$ where $\varepsilon(X)$ and $A(X)$ (the so called conductor) are real numbers which can be defined unconditionally.

1) How is the conductor defined?

2) It is a theorem or essentially part of the definition that $X$ has everywhere good reduction if and only if $|A(X)|=1$?