All excellent questions, thanks!
Yes, we mean the first 5 Tapas chapters/episodes—apologies for any confusion!
The second and third questions have a similar answer. We take a number of factors into consideration while reviewing submissions, so I can't say what might increase or decrease your chances of being selected. That said, we'd love to know if you've had success or have a non-exclusive contract elsewhere, and you can also let us know if your novel is already available on Tapas and how things have been going. Please do include that information in your cover letter.
If you either decide to edit your novel or take is elsewhere and see success there, sure thing, we can take another look down the line.
Finally, you'll likely hear from us about two weeks after submitting, depending on the volume of submissions at any given time. I'm certainly going to do my best to let everyone know our decisions, but feel free to follow up if you haven't heard from someone after two or three weeks.