lucid's link goes in to detail. But in brief:
why in the world did you begin C2 without fixing the most atrocious bugs in C1 first?
Because we couldn't - many of them are deep-running design flaws which would take more time to fix than to start with a clean slate. Construct 2 is that clean slate.
) When I use the sprite-editor and load up an existing image file and save it, it cuts the image literally in half, it cuts the bottom half of the image completely off.
Could be a graphics driver bug, are your drivers up to date? Unlike C2, Classic uses DirectX for the image editor which means it's vulnerable to driver bugs. Part of the reason C2 uses a software rendered image editor is to avoid issues like this.
ou need to fix these bugs
Like I say, we knew there were big problems, and we knew we could do better, and that's why C2 exists. Also you should remember you got Construct Classic for free, and it was written entirely by volunteers working in their spare time.