as a wife of a survivor i can answer question 1 pretty well. he wants you to know because if you then still understand him, he can come up with a little more trust towards you. he didnt lose you over something he assumed he would, but you stayed. thats a huge proof for him and for that he wants to trust you enough to let you look into his world a bit more. you should appreciate that. the plan with having no secrets in the healing process is the only one that will actually work. you are lucky he can trust you enough to do this.
to question 2: its normal that first there is some euphory and a huge relief after knowing he has told you the CSA but you stayed. he knows it wont be easy. the wish to heal comes from him, he got a shock being caught and really scared to lose you, thats the perfect combination for a survivor to take it seriously and try his best smile (they are kids inside, he has motivation and a good reason, wanting to stay with you, probably the only person he has ever felt some attachment to)
to question 3: yes you should. part of the healing is to get rid of the fantasy part and stay in reality. get rid of all the fantasy part for now. his fantasies are abuse results and you dont want abuse results in your sex life, and so deoesnt he. they are very contraproductive in healing, so dont. he needs to agree to that and stay honest. if anything unwanted pops into his head, he needs to stop, tell you and go on when its gone and dealt with.
4. your feelings are totally normal. you wouldnt be normal if you felt anything else. it will become less, but it wont fully go. thats a result of him having traumatized you thru his betrayal. you are now scared and this fact can end up in an addiction to a person, so do be careful. i would like to advice you a book: http://www.amazon.com/How-Break-Your-Addiction-Person/dp/0553382497
5. thats a healthy plan, but its not easy to work out. you too need to realize the ride from your side wont be easy. when he is fully honest and until months of unwanted images are over, after stopping the fantasy and the dissociation part, then only you will get some sort of relief. but your guards will always be on!

he is lucky you aer there, you are talking sense adn you are a really understanding woman! in fact he is damn lucky. and he knows that. make sure he doesnt forget that.
but you are also lucky that he told you and he wants to change something about his life with you, for you and himself, because it coudl have gone much worse. believe me, it could have!

good luck!
everything is always okay in the end, if it's not, then it's not the end