I have used a kneaded eraser from Faber Castell since I began drawing. I love working with kneaded erasers a you are able to sharpen them as you wish and it's easy to clean rubbing it on a piece of paper. You are also able to make it very sharp for thinner hairs and small highlights on lips, eyes etc.
I never use regular rubber erasers, in my experience they damage the paper and I just don't like the feel of it.
The eraser pencil is one of my favourite tools when working with lighter hairs and need to erase very precisely. My eraser pen is of the brand Tombo. You can get them in 2 styles; with a flat and a round tip. I prefer the round as it's only 2mm (0.08inches) in width.
I've only used it for a couple of years but I find it very helpful in addition to the kneaded eraser.
Faber Castell also has an eraser pencil which I used for a short period of time. It's very similar to a normal rubber and you need to be careful not pressing too hard with it and erase too much at the same place (or the paper will break). It can be a little tricky to sharpen and you need to sharpen it often when using it for fine thin hairs.
That being said it's a good alternative to the Tombo eraser pencil if you are not able to get it.
Through the years I've had different favourite sharpeners. I used to buy the wooden ones as they were light and great.
When they stopped offering them in the Danish art shops I bought some cheap metal sharpeners from a local toy shop. They worked great but easily stopped working.
My current favourite sharpener is from the company Staedtler.
They come in different variations; the ones I have tried have all been great.