My guess is that you haven't received a response to your questions about how long it takes to develop instruction, etc. because it varies widely based upon the content, the skill of the person, the quality of the internet connection, and so on.
First question: "About how long does it take to convert a classroom lesson (about 50 minutes) into an online class?"
Depends upon what the learners will be doing in those 50 minutes. What do they do in the classroom lesson? What are the learner outcomes? Is there an assessment? (These are just a few of the questions to consider.) If you want them to read an essay that is already written and then answer some discussion questions, this might not take long at all.
Third question: "About how long to create a quiz or exam?"
To type in the questions from scratch, it takes a couple of minutes per question depending upon typing speed. To upload a batch of questions, it might be less time depending upon how adept you are at converting files to a certain format, say GIFT or AIKEN to use those filters.
Hope this helps,