Edit Zoom interview about company

We had a conversation with a customer about their experience of our product and service. We'd like this edited to:
- add subtitles (there's quite a lot of 'um'ming and these need to be manually cleaned up a bit to make sense without the audio). I can provide an edited .srt with most of this done but the timings and things are now not quite right and need tidying up.
- focus on interviewee (ie crop the video to the person speaking, then switch back to two screen Zoom recording when we ask a question)
- add title screen and closing screen slide
- export the full length whole video
- produce 6 excerpt clips around 30 seconds long from the overall video, with their own title screen.

The source video is an mp4, 72MB, 1280 x 720, a bit over 13 minutes long.