I do some of these from time to time, and weirdly, the 'back' button on the browser helps temporarily.
#3 is my usual mode for initial watching, but I'm prone to go with suggestions from that when I'm watching. Sometimes, even with best intentions, it gets messy.
If you're on desktop, installing Stylish and removing YouTube's comments and Suggestions panes is a huge win. You'll still see suggestions in-video, but those are slightly less annoying.
(I've also noticed that, well fed and pruned, YouTube's suggestions actually tend toward useful these days, though that's with exceptionally aggressive pruning.)
Yet another option is to use youtube-dl to download and play content locally. I do this pretty much exclusively on desktop, and find it quite helpful.
#3 is my usual mode for initial watching, but I'm prone to go with suggestions from that when I'm watching. Sometimes, even with best intentions, it gets messy.
Number 4, that would be most excellent. :D