You can extract one side. but unless 60% of that side is capped I wouldn't.
Feeding back for winter stores is pretty much just leave on hive, if you have to get ready for winter, just pop those nectar frames in your deep freeze, and do the Granulated sugar method, (mountain camp dry sugar), or I make fondant - hard fondant candy, and I think I've posted the recipe.
This post discusses winter feeding prep https://www.beekeepingforums.com/threads/hi-i-need-some-advise.12041/#post-205593
Feeding back for winter stores is pretty much just leave on hive, if you have to get ready for winter, just pop those nectar frames in your deep freeze, and do the Granulated sugar method, (mountain camp dry sugar), or I make fondant - hard fondant candy, and I think I've posted the recipe.
This post discusses winter feeding prep https://www.beekeepingforums.com/threads/hi-i-need-some-advise.12041/#post-205593