1. Yes, that’s possible. You can structure the test chapter in sections and randomly pull any number of questions from each section.
2. Setting a time limit for completing the test is a standard feature. You can execute any action you like when the time is up
3. You can create a certficate page and fill in variable values from the course / the current attempt. All reports concerning all participants or all attempts of the same participant are beyond the limits of the current attempt. I don’t think there’s a way to do this with Lectora alone.