Help me understand Lightroom profiles and RAW imports.

The edited icon appearing without doing any edits is a bug that is present in the recent Lightroom version. It will be fixed soon.

There is no such thing as a truly raw preview. If you just push the linear data in a raw file to a display it would look very very strange. Raw data has to be interpreted according to a model of the camera sensor response and gamma corrected to display correctly. There is no such thing as a pure raw view. It is always interpreted. Adobe uses profiles that are similar to image styles in many cameras. The Adobe profiles are generated from shooting reference charts in controlled lighting conditions. They are very close to accurate in most cases but they differ some in relative contrast and color saturation. The closest to a 'objective' interpretation is when you use the Adobe Standard profile. Adobe Neutral is very low contrast but basically the same. Again there is no correct choice. It is only possible to be perfect if you shoot reference charts in exactly the same light conditions you shoot images in and create your own profiles from that because it is not possible to create cameras that have the same color response as our eyes. This leads to color metamerism where the color we perceive with our eyes or with a camera changes depending on the light that impinges and changes differently for the two media (eyes and camera). This is normally not a big deal if you're dealing with broad band light soures like the sun but can be an issue for very monochromatic light sources such as LEDs or fluorescent light sources.

The camera matching profiles are created to mimic the in-camera jpeg rendering. That includes the jpeg preview always done in camera and embedded in every raw file.  Camera makers like to go a bit further and their jpeg rendering is usually very specific to their brand. This is not inherent to their hardware, it is just a data modeling choice to make their jpegs look like what you expect from a Nikon, Canon, etc. camera. You know: 'Canon renders reds much better', 'Nikon's greens are so much nicer', etc. The sensor is not really that different. It is just how the raw data gets interpreted.

There is always a slight amount of noise reduction and sharpening done indeed. This corrects for the small amount of blur that is inherent to cameras using a Bayer mosaic sensor. In those sensors, every pixel only detects a single color channel. Usually this is laid out in blocks of four sensor pixels where two pixels detect green and one red and one blue. Raw converters take this data and use special algorithms (demosaic) to interpolate a full R,G,B triplet at each pixel location. This is another way in which raw always has to be interpreted and there is no objective way to do this. Hoewever, this fact unavoidably introduces a small amount of blur that the default sharpening compensates for. The small amount of noise reduction is also there to slightly compensate for the noise that is inherent to the physics of photons (their particle nature in this case). Every image has an inherent amount of noise. There is also noise introduced by the math of the demosaic algorithms. So both of these have good reasons. The default amount is very very low and much lower than cameras do in their jpeg previews. In most cases, to optimize detail, you need to optimize the sharpening sliders anyway.

If you don't like the small amount of sharpening and noise reduction as the default, just set the default treatment for raw to a zero sharpening and noise reduction preset or create your own preset and set that as the default.