I claim that replacement is provable in the theory SF+"every set is finite". One proves any instance by induction on the size of the domain of the function. That is, a given instance of replacement says that if $A$ is a set and we have for every $a\in A$ a unique $b$ such that $\varphi(a,b)$, then the set $\{b\mid \exists a\in A\, \varphi(a,b)\}$ is a set. Suppose this is true for all sets smaller than $A$. Now, remove one element from $A$, apply the induction hypothesis, and then add in the missing $b$.

So the answer to your first question is yes.

I claim that replacement is provable in the theory S+"every set is finite". One proves any instance by induction on the size of the domain of the function. That is, a given instance of replacement says that if $A$ is a set and we have for every $a\in A$ a unique $b$ such that $\varphi(a,b)$, then the set $\{b\mid \exists a\in A\, \varphi(a,b)\}$ is a set. Suppose this is true for all sets smaller than $A$. Now, remove one element from $A$, apply the induction hypothesis, and then add in the missing $b$.

So the answer to your first question is yes.