(please consider, I have zero video recording skills, neither know video editing software. What I know is no more than there are video/audio codecs, container formats, streams, and I also aware that video/audio sync could be a problem)
Context
I would like to create acoustic guitar demos of my home playing.
Sound quality do matter, so audio of simple iPhone video recordings will not do it. I have established practice how to record guitar audio (with my mike, amp) and I have also established audio recording practice, this question is not about this)
Now I would like to do video too, not just the audio. My very first idea is concurrently record video with my iPhone, somehow transfer to my Windows 10 PC, and then edit the video and (put and sync?) the high quality sound with the video together.
Question
Q1: Is this a good idea? (I've checked how to connect my iPhone cam with PC, but it seems no benefit, it has delay, quality loss, etc)
Q2: I would not like to do sophisticated video effects and postprocessing, however I would like to have multiple recordings (multiple audio/video takes, for example to compare guitars), and "switch" between them (10 secs from one, then 10 secs from other, then back) in the final result. The two streams from two sources (audio and video) must be synced, but preferably not the price of sound quality, video quality is not so important. What free software (Win 10) is recommended for this task?