no.1 : Still, I wouldn't talk to them - Nevertheless, I wouldn't talk to them : they have done something which means that you should maybe not talk to them.
no.2 : I still wouldn't talk to them - I would continue not to talk to them
no.3 implies that you are talking to them, but perhaps you should not be, because they have done something 'bad' or wrong
no.4 is not grammatically correct