S.T.
oh, my dear. i'm SO glad you are considering leaving this ogre. these are good questions to ask. start here, but then you really really do have to take these questions to someone who can answer them for you with more than personal experience. you need a lawyer, and there are agencies to help you get one if you can't afford it.
the frequency of his visitation will be determined between the two of you, and by the court if you can't decide. how often do you think he'll want to? how often are you okay with it happening?
i think a much more important question to ask is 'will my child be safe when he's with his dad and i'm not around?'
i don't understand the second part of the question. you're not 'supposed' to do anything in particular. the list of things you COULD do is endless, from going to work to taking a nap. i hope at least some of the time is spent on self-help so that you don't fall back into unhealthy patterns, and end up finding a clone of your husband because it's familiar.
you need to have a quiet conversation with your boss if you really think your husband might call your job. if your boss has a heads-up that vindictive phone calls might happen, the plan will backfire and your husband will be the one who is humiliated.
he said he will what himself if you leave? of course he's going to blame you for tearing the family apart. refusing to take responsibility is what ogres do. don't listen to that.
keep gathering information and arming yourself. you're on the right path.
stay strong!
khairete
S.