I actually started off doing exactly the same thing: drawing on paper and then coloring digitally. Over time I wound up liking drawing digitally more but yeah.
Anyway, there's pretty much two different formats here that are common: One-page-per-episode, which is the more traditional format (similar to manga), or the webtoon format, which is that really tall and long format you've seen.
Examples of one-page-per-episode:
https://tapastic.com/series/Engelbaum
https://tapastic.com/series/West
https://tapastic.com/series/The-Property-of-Hate
https://tapastic.com/series/D_Fate
https://tapastic.com/series/Wednesday7
Examples of webtoons format:
https://tapastic.com/series/keol
https://tapastic.com/series/ReSet (kind of close to the traditional format, but longer than normal, probably close to what you're aiming for as a hybrid)
So yeah, you can certainly do it in either format and there are pros and cons to both. Personally I went with the more traditional format because I would like to publish a physical copy someday, and converting the webtoons format to physical print sizes sounds like a nightmare.
Uploading shouldn't be an issue, but it you will need to learn how to trim the images to need file size requirements. Here's a handy tutorial on splicing comic files for size: http://iingo.deviantart.com/journal/PE-How-to-Splice-Comics-585026025