Take 4 x 3.5-hour videos, remove noise, split into 21 chapters.

I have four videos of an on-line course recorded over two days on Zoom at 1686 x 768 on mp4 format. There is a hiss on my headphone mic that needs to be removed. Then the videos need to be split (and in a few cases combined across breaks) to correspond to the 21 chapters in the manual. Sound and picture quality must not downgrade. Use whichever editing tool you like (but tell me what you used) Compress the final products with Handbrake.