1) ATF will approve the application if the applicant:
Is 21 years or more of age;
Is not prohibited from shipping, transporting, receiving or possessing firearms or ammunition;
Has not willfully violated the GCA or its regulations;
Has not willfully failed to disclose material information or willfully made false statements concerning material facts in connection with his application;
Has premises for conducting business or collecting; and,
2)$30 for 3 years
3) You need to send a copy of your app to the head of your local law enforcement agency. I don't know what ATF does as far as a background check. If you're a convicted felon, you might want to think twice
4) Varies. Should be 30-60 days, if what I'm reading lately is an indication
FWIW, the search function is your friend...