[kahynickel]

second electron affinity is positive because the addition of a negative electron to an already negative ion requires heat due to the repulsion between the electron being added and the already present electrons.

Then why the First electron affinity is negative, it must be positive. Won't there be repulsions between the electron being added and the outermost electron of an isolated gaseous atom say chlorine ?? 

[Enthalpy]

What about the positively charged protons?

[kahynickel]

Positive protons attract the negative electrons.

protons attract electron and want to add them to their outer shell. but won't there be repulsion between this added electron and the already present electron in the outer most shell, although there would be attraction between the the protons and electron ?? 

[Enthalpy]

Yes.

As many protons and electrons in a neutral atom. Far enough, an atom doesn't attract an electron, the net result is zero.

If for instance the electrons distribution at the atom has spherical symmetry, they create the same electric field as if their charge were concentrated at the centre. Same charge same flux. Field of spherical symmetry too same field.

But if an electron approaches a neutral atom, all electrons rearrange a bit, precisely because they repel an other, so their increased mean distance reduces the repulsion. The protons keep attracting the additional electron as much. As a net result, a neutral atom attracts one additional electron.