A: No plagiarism checker, you can assume all scraped content is not unique and re-written will be anywhere from 50 - 75% unique.

All AI content is unique.

You can use copyright free images (eg pexels)

Videos are just youtube embeds so you just sharing it.

If you use the AI writer to do re-writing then yes, re-spins cost cost credits.
You can use Google gemini to do respins, which in this case means its free.

SCM comes with free simple re-writer for English and Vietnamese.