Of course I don't know. :)

However the most common causes for these things are:

• RAW is "softer"
  1. The RAW image isn't 'softer' - JPEG image is doctored in-camera usually with quite aggressive sharpening. Especially on entry-level cameras this sharpening is 'yelling' sometimes and can cause artifacts
  2. Besides sharpening, JPEGs usually have in camera some curves applied to increase contrast and 'push' having as a side effect a perception of increased sharpening.
  3. Noise reduction applied in post-processing can make the image look softer because (usually) removing noise means removing detail.
  4. Psychological effect of more light. A lighter image feels/appear sharper than a darker one. You can play with a properly exposed photo by moving the 'Exposure' slider to make it a little darker and after this a little lighter. The first one is more "flat", the latter one has "more" detail.
  5. Also, depending on current camera program ('Vivid' etc.) there are also other Color manipulations like Saturation and/or Vibrance boost (and others) which also give the impression of 'more sharper/pop'. (HDR I'm looking at you...)

In your concrete case, I think that at least the first 4 points above apply.

• JPEG has different dimensions than RAW

Yes, known fact. And more: it differs depending on what RAW conversion engine you use. See here:

It has to do mostly with how the demosaicing engine treats the near-edge R, G or B pixels in order to compose the actual picture.

For reference, Photivo uses DCRaw.

Also, some JPEG engines truncate the dimensions of the image at multiples of 8, other ones do not.

So it isn't a surprise that the dimensions are different. I know, it doesn't feel natural, but this is the way it is. Perhaps when we'll get rid of the classical single color (Bayer/TransX etc) sensors we'll get rid of these oddities as well.