Have tried various socks and always come back to Smart Wool, which though expensive do live a good life if looked after. Avoid Teko, which look similar when new but don’t have the same longevity. Having said that I am also using the Costco wool ones which are fine too and mega cheap.
Any sack above thirty litres will need to fit properly if fully loaded so as above go to a decent retailer who will let you try on the sack loaded and spend some time with it on your back.
If you can’t already, take the time to learn to navigate with map and compass. Use GPS to augment this learning if you don’t have any skilled buddies, and consider a formal course. It’s a great feeling being able to get out at night, in any visibility, snow, etc., knowing you can move safely and will give you a smug glow….