Some maps put the number of native speakers at around 4000; are there any numbers on fluent speakers of Cork dialect?

Not likely probably people who can speak Irish to a certain degree, but for fluent speakers on the Cork dialect would be less than 150 or 100 even, around 100 I would say.

Hard to say, but 100 seems very low. I know that in the top three electoral districts in the Cork Gaeltacht in terms of daily speakers (2006 census), the total of habitual speakers was around 430. This includes what remains of the former fíor-ghaeltacht (Baile Bhuirne, Cúil Aodha etc). The total of 'Irish speakers' was well over 1,400 (obviously many of these individuals only use it in school now) so I imagine there are still a few hundred native speakers.

I know a native speaker from Inchigeela,which is not- or no longer-in the GaeltachtThere are probably a few dotted around neighbouring villages,like Clondrohid,Cill na Martra,even Macroom.Cúl Aodh is the core though ,and a fluent speaker once told me it was 'kept alive by about 8-10 families'.Long may it last.

Native-Irish speakers are "sprinkled" through-out the community and respected in all parts of the country. They are to be found working as teachers, gardaí, civil servants, journalists, etc. They form the backbone of local groups of parents who establish and maintain Irish-medium schools, Na Gaelscoileanna. Just because they live outside the geographical area of the Gaeltacht does not mean that they don't actively use their first language and encourage others to learn Irish also and help promote the language as much as they can. Outside the Gaeltacht areas speakers of Irish make themselves understood to each other regardless of dialect. It is a big mistake to regard all speakers of Irish outside the Gaeltacht as "learners" of "Revival Irish". Most of the thousands of good everyday speakers have roots in the Gaeltacht. Some of us in Irish-speaking areas that no longer remember the language.