first..yes ..it is zero ..field inside a conductor is zero...be it a sphere ..or a banana ...

second ...charge transfer does not specifically mean ..the transfer of protons or electrons ...

dumb question : how will u give a positive charge to a body ?

answer : by taking its electron away ..

dumber question : how will u give a negative charge to a body ?

answer : by giving him some of your electrons ....

so...

the solution for ur second question is :::: that the charge rearranges in the manner that ...all the charge given to it APPEARS to be at the surface..

key word: APPEARS

now the dumbest question will be :: nugo ! explain wat do u mean by appears ...and i aint gonna answer that ...

(am i being rude?)

If shape is spherical, field inside zero, otherwise not in general.  

No, in case of negative charge all excess free electron come to outer surface.

In case of positive charge, outer layer of atoms left free without free electrons so it is like positive charge on surface

All this is required to have zero net electric field inside metal in electrostatic  equilibrium and simultaneously satisfying gauss law.

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nice qes gear

 the answer as follow