Once again the new version renders the previous version saves incompatible and we are forced to start from scratch...
There's an option for that. Unless you have save points at every achievement, it's fairly pointless anyhow. The video walk through shows you how to get to the content in a quick amount of time. You can find those here:
You must be registered to see the links
You would literally need saves at all the key events to try to skip through and maintaining backwards compatibility with old versions isn't worth it because of the amount of bugs it causes.
Also, you can simply use the Ren'Py Save Editor and change the save_version value if you are that hard up on not redoing anything. If it works without issue, cool. If not, you lost 30 seconds of your life trying.
There is no CG file that I know of, I don't think anyone has taken the effort to do so. Many of the VN's art pieces are broken apart and layered heavily, so screenshots would probably be a better bet.
The closest thing to a CG would be Patreon art they post AFAIK.