Assuming you are talking about Harmonia, it looks like she just followed the standard. Base color, shading separating each section of hair and some at the top of the head, and then just a few curves of highlighting where the hair hits the light. The standard zig-zag shape is still used, but it’s not as discernible. The only thing unconventional I see about the art is the texture used. It’s a simple canvas pattern that she probably uses as a brush (either in placement of, or as the removal of, some of the darker shading.) It’s also slapped onto the darker parts of clothing.
I think the eyes are more interesting. It’s very defined. I can’t find the balance to replicate it.

There’s a whole bunch of engines to use. Reallivemax, Renpy, O2, Unity, you could find a large amount with a google search. They all do pretty much the same things, though Unity has extra functionality.
I’d argue against that. Lots and lots of VN readers have put it off. Whether it’s the art style, the length, the translation, the availability, the mark it may have on their history with the anime. People like excuses.
Clannad probably wouldn’t even on the board for some people if the translation wasn’t happening.
I wouldn’t be surprised. People like to milk those remakes and remasters.
Australia wouldn’t be surprised either >.>