Visual novels

Not on Steam, sadly. I'm pretty sure Steam declined the chance to get the Higurashi visual novels on the service, sooooo... it doesn't seem like they'll have VNs anytime soon.

There's tons of websites that have them though. A large percentage of them are... naughty, so be careful. Narcissu is a clean one.

Nop, but I used to.

A quick search into the VNDB results in around 700 visual novels and other games with ADV/VN parts of considerable length with a full or partial English language release. So I'd gather that there are a few you missed. ;)

It is going to happen, I spent some effort making sure of that ;)

Sumpin like an interactive movie. Imagine Fahrenheit or Heavy Rain with hentai girls :/ As for me, it's a text quest/adventure.

Type up a story on a computer, draw characters and backgrounds, add music and/or voices to it, then add choices that the player can make (which is optional).
Have this all play out like a slideshow and there ya go, that's a visual novel. :3

A Visual Novel usually looks like this: 1, 2, 3, 4, 5. Full screen text with overlying image is the main clue to identify them. They also feature heavier narrative than ADVs.

While the Japanese style adventure games, which also gets called as Visual Novels outside Japan look like this: 1, 2, 3, 4, 5. Texts appearing in smaller boxes, most usually at the down center is the tell of an JADV.

While these visual presentation styles are frequently used in all kinds of mostly Japanese originated games the defining factor of a VN/ADV is the presence of narration, non-VN games only have dialogue and that is considered to be the difference.