The long strip format is not easier to read there is so much dead white space that i'd risk getting carpal tunnel buy reading the amount of content that a manga has on one page. If i where to say your comment is currently in manga format then to convert it it manwha format every time you hit space instead hit enter 3 times
Err...'scrolling' does not involve hitting the enter key. Typically it's the Mouse Wheel or finger on mobile devices.
The long strip is so you can have a single page and scroll through images.
In any case with Manga you'll get blocks of images in cells that simulate book pages and Manwha will have a string of images without page borders.
In regards to scanlators you'll see more manga scanlation groups than you will manwha. Because the fandom is used to translating japanese rather than korean, However, because manwha are distributed online there is more digital localizations and digital images are easier to come by than purchasing a copy of Shonen Jump and disassembling it to run the pages through a scanner. Its interesting to see Korean Manwha picked up by groups for translation through a Brazilian localization site because the only translator they have is Portuguese to English.
Also interesting fact, there are no spicy Manga.
There are mature manga, but nothing official can be considered explicit adult content.
Any explicit adult manga you fine are doujin which are fan comics and not officially published, though there are some that come close ("Creature Girl: Hands on Field Diary"

) they usually stop at extremely suggestive to skirt past censors (To Love Ru, Monster Musume, etc)
On the flip side there are official adult manwha. Since they go straight to the web without having to go through publishing laws there are less restrictions on their content.