Both the Problems are Trivially Decidable. We know that Every CFG (Doesn't matter whether it is ambiguous or unambiguous ) generates a CFL . So, If someone comes to you and asks you "$G$ is a CFG, Will $L(G)$ be CFL ??" ..You can just trivially say "Yes".
Or another way to understand it is as following :
Decidable problems mean that there is Some Algorithm to solve them (Though Algorithm word is not precisely defined but I am assuming the same meaning of this word as you know it)..So, This Problem is decidable because I can write an Algorithm for this Problem... My Algorithm will take whatever CFG $G$ you pass as input and Will (without calculating/doing anything) just simply output "Yes". $O(1)$ time algorithm(vacuous algorithm)..
When the Domain is Unrestricted grammars i.e. $G$ can be any Type-0 grammar and then if it is asked "whether $L(G)$ is CFL or not" ....is Undecidable (Because of Rice's theorem)