Is it a ionic compound?

It is an ion, but not a compund.
Thus, polyatomic ions is not equal to ionic compound
*KMnO4 is ionic compound.
MnO4- is Non metal.

say accurately, we cannot use "real charge" to discribe Mn in MnO4-.
We only know is that how the electron is arranged in MnO4-.
It is the reason why we use imaginary charge--- to discribe.

Mn is 2+ in ionic form
There is 2 electrons in 4s orbital
Mn2+ [Ar]:3d^5

MnO4- is a polyatomic ion
it's different from ionic compound
because ionic compounds consist of cations and anions
MnO4- is just a kind of polyatomic anion

KMnO4 is an ionic compound
it's because it consist of K+ and MnO4-
there is strong electrostatic attractive force between the ions

for real charge
one MnO4- ion carry one negative charge
you can find the charge at the upper right
that is, the - sign in MnO4-
we cannot say the real charge of Mn
it's because it has been formed an ion
or, another substance
so, forget about Mn
focus on MnO4-