I'm so slow at knitting socks, but love it anyway. They're the perfect travel project so I've usually got a pair on the go in my little drawstring bag and have got myself into all kinds of conversations with strangers in public as a result.
The ones pictured you might recognise as "Hermione's Everyday Socks", and they were technically the third pair I ever made but the first two were awful and we're not counting those. First proper socks, hurrah!
The yarn was a weird cone of nonsense that I'd picked up from a shop called Yarnia in Portland during a big month-long USA road trip we went on in 2015. Basically you chose your fibres and colours and they'd wind a cone of yarn to that specification.
Or, if you're a wimp like me, you could just buy a pre-wound cone and trust it had the right stuff in it for socks which is exactly what I did.
These babies lasted me until late last year then started to wear through on the ball of the foot, I've kept them safe and can hopefully learn to repair them. Any advice in that area would be very welcome!
The repair method you're asking about is called darning! If you've got yarn leftover (or even just yarn in the same weight class), you can patch the holes without needing to take the socks apart. This article explains how to do it and you can get darning eggs on Etsy but I've also seen tennis balls recommended. Anything that you can use to hold the sock like it's being worn while you're working will do it. Sock darning tutorial's over here.
If/when the heel wears out, you can also replace it with an afterthought heel I use this method once in a while for different colored heels instead of doing a heel flap/gusset. You can also use this for different colored toes and repairing them as they wear out. How to do an afterthought heel For doing both of these, I'd recommend putting in a life line on the row of stitches below what you're removing to hold the rest of the sock while you work. (Any contrasting sock yarn or thin nylon cord would work fine for this).