a. No one outside of the investigations no anything useful - not even the president, according to himself.
b. they did not have access to the deleted emails like FBI has
c. Some issues involved:
did she share classified information in an inappropriate way? There seems to be no doubt that she did that.
Is what she did illegal/criminal. Two issues here:
i. retroactively classified material (leading to the debate about agencies tendency to "over classify")
ii. material that by its very nature is classified at birth regardless of whether it is marked as such. There seems to be evidence of the latter - that she inappropriately shared information that she should have known was classified at the time.
Apparently the key point here is intent, that is, whether she deliberately shared secret material with someone not authorized to see that material. I do not think people expect her to deliberately trying to hurt America or jeopardize its safety. What she did was obviously careless and poor judgment but there was no intent to reveal state secrets to someone who should not see it. However, there may be one thing lurking that nobody is talking about (pure speculation). She may inadvertently or deliberately have revealed secrets to some of her business partners/donors/friends in order to for them/her to gain a business advantage. She may have been careless to not sufficiently hiding her tracks. I mean, she does have a history of being careless and having poor judgment, she might have slipped in a way that reveal criminal intent.