About the scroll format: tbh, this is kind of a recent(-ish...?) trend that started with Webtoon and Tapas, which are mostly mobile app based. Problem is, since Webtoon and Tapas ARE the two biggest platforms to host webcomics and grow an audience, you'll see a lot of pressure to turn your comic into a vertical scroll format, even if you never planned to do it that way. I myself started to post in a traditional format (and I still do it on my website and on ComicFury), but yep, definitely felt the pressure to switch to a vertical format for Tapas/Webtoon. It is not mandatory, of course: on Tapas especially, you can get away with a traditional print format... but Webtoon seems to be more strict about it.
That said, I've also seen comics in traditional format doing pretty well on Webtoon, like Closely Knit (which was even recommended by the staff at some point), Istrevelia and Crankrats.
For traditional print format, I think ComicFury is truly the only platform left with a decently sized audience that won't make a fuss about the kind of format you choose. FlowFo and GlobalComix seem to be fine with either format as well, though neither seems to have much of an audience (it's also true that FlowFo is VERY new, though).
As for Tapas and longer episodes... problem with the site is that it doesn't really have a way to bookmark your progress mid-chapter. So if you stop reading a multi-page chapter halway through, the next time you come back to it, you'll have to scroll aaaaaaaall the way down to find the panel you were reading again. Webtoon works a little better in that sense and will load the page starting from the point you were reading last time.