1. You're correct that the weather conditions also affect the weather rating. We review these from time to time and will take note of your feedback.
2. All the change groups are fully depicted in the TAF inspection window. I guess you are referring to the graphical depiction on the map? If so, we do have plans to vary that for departure time in the future.
3. There is only so much work we are prepared to do in accommodating non-standard TAF/METAR formats, but in this case since CAVOK has already appeared you are correct that we should discard the apparent visibility figure.
4. For the time being SkyDemon ignores SNOWTAM.