Price: we'll use a freemium model, starting in Q1 2017. Pricing will be similar to other tools in the market.
Trello/imports from other apps: we have one click imports for Trello and Wunderlist, & working on more. We're also in beta with Zapier. You can see our Trello comparison here: zenkit.com/trello
Unstable/Problems registering: sorry to hear there are issues here! HN was pretty unexpected :) we'd be happy to fix this on a case by case basis. Please send us a short note to hello@zenkit.com with your username / registration email.
API/webhooks: we're working on publishing our API and we hooks. We'll make them public as soon as we release our iOS app at the end of this year.
Localization : support for more languages coming in Q1-2 2017!
Tutorials/onboarding: we're releasing videos in the next week or two. Again, HN was unexpected :D
Feature requests : thank you so much for your requests! We're taking note and will definitely keep everyone updated with new features. (we've already got a lot of great stuff in the pipeline!)
Feel free to get in touch via email if you want to chat!