Prefer the 5340 and not this model here. Whether you are experienced or not, the 5340 does not have the issues that this one has. The 5640 here, visually it is a bit shorter and has a longer tip, but the biggest difference between them is the mechanism. This one here works like mechanical pencils of 0.3mm/0.5mm/0.7mm/0.9mm. That is, it gradually pushes out the tip with each press of the button. This would be useful if it could be used for technical drawing, but as known, these pencils are for sketching/freehand drawing and maybe for quick notes. This is one thing, but the real problem is that the mechanism has issues, which most people who have bought it complain about. The 5340 is the classic lead holder system, which is incredibly convenient for sketching/freehand drawing and due to the simplicity of the mechanism, it has no issues.
As for the sharpener, while they usually have it on the button that unscrews, I would suggest having this one only for emergencies if you happen to be away from home. For everyday use, a simple sharpener, like the ones we use for all pencils, is what you need! Specifically, for 5.6mm, I would recommend the metal M+R sharpener, which comes in a transparent plastic case and has 2 extra blades at the bottom! I have been using it for 2 years and I haven't changed the blade yet... It usually costs less than 1 euro, others have seen it for exactly 1 euro. It produces the perfect tip for 5.6mm, just like with all sharpeners, we don't sharpen continuously and obsessively, but carefully and with regular checks, so as not to make the tip too thin and therefore fragile.
The Koh-I-Noor company produces the best tools for sketching, as well as the best Red Chalk or Sanguine, which for some reason usually does not mention it with either name, but Russet Sepia. In reality, it is the closest thing you will find to Red Chalk and together with Dark Sepia, they are my favorites for sketching! They also produce them in 5.6mm and in wooden pencils, where in wooden pencils, they call the Red Chalk by its correct name and it is exactly the same material, which in 5.6mm tips, Koh-I-Noor calls Russet Sepia!!

It writes somewhat faintly and often needs sharpening (that's why 4 stars). Otherwise, you enjoy holding it in your hand and it is beautiful.