This is all very straightforward .... once you get the hang of it.
Yes you can use the same setup in an Intro or Outro as the main mission. In the main mission select what you want by dragging a box round it, hit Ctrl C to copy. Go into the Intro and hit Ctrl V to paste. I use a dummy unit which I put at a very identifiable place so that placement of units can be replicated exactly. Copy and paste does not dump them in exactly the same place, so you will need to move them a little. As long as they are selected you can move the whole lot together by moving one.
Intro - plays before the Briefing
Outro - plays after the debriefing
Cutscene - plays whenever you like, can be on mission accomplished or as soon as the mission starts. You can do a cutscene with the camera effects ina trigger but it is MUCH BETTER to use a simple camera script. Fortunately that is easy to do. Read snYpir's camera tutorial and then messiah's camera.sqs tutorial.
You end a mission with a trigger. Find the box in the trigger screen called "type" and change it to End#1. When the trigger is fired, the mission will end.
To make the mission end from a mission accomplished cutscene, you need a variable. The last line (before exit) in the cutscene will be something like
endmission=true
and in the mission you will have a trigger
type: End#1
Condition: endmission.
Now head over to the tutorial depot and download the
Tutorial Mission. I created it specially for people like you. It contains answers to all the questions in your post. Play the mission and then study it in the mission editor. Come back and ask if there is anything you don't understand.
If you are unfamiliar with scripts snYpir's Introduction to Code Snippets will come in handy.
snYpir's OFPEC Guide: Making Missions and my own Macguba's guide to mission editing for beginners both contain lists of tutorials which are more or less essential reading.