Let $X$ be a smooth proper curve over a number field $K$, and let $f : X\rightarrow\mathbb{P}^1_K$ a degree $n$ map unramified outside $\{0,1,\infty\}$.

I've read in various places that something of the following type is true:

$$\text{$X$ has potential good reduction at all primes $p\le n$.}$$

Does anyone have a reference for this?

Secondly, could something of the following form be true: $$\text{There exists a finite set $S$ of primes, independent of $X,f$, such that $X$ has potential good}$$ $$\text{reduction at all primes $p\notin S$ which do not divide the ramification indices of $f$}$$ (Ie, does anyone know of a counterexample to such a statement?) In particular I'd be interested in seeing a counterexample in the cases where $S = \emptyset$ and $S = \{2\}$.