Monthly. Actually it's stated on the webiste: http://www.blynk.io/plans/
We haven't seen anyone so far who reached this limit. We will publish a calculator to make it easier for you.
Here are some numbers:
100 devices,each making 1 req per minute would cost you (apps + cloud) ~$200 / Month
1000 devices, each making 1 req per minute would cost you (apps + cloud) ~$300 / Month
It's rather a question for you In an unlikely case if Blynk shuts its doors, your app will stay in app stores for another year, or we can transfer it under your account. Or we can even publish it initially under your accounts if you have them. We will also offer you migrating to your own server.
Even amazon sometimes is down... If you are running your server - it's on your shoulders. If you need 99.99999% uptime we can set it up for you. And of course it's not for $99/month
Since Blynk launched in May 2015, our uptime was %99.9
price is listed on the website. We can localize app. It would be an additional fee. DM me if you are interested.
All Blynk widgets are supported. Timer widget is accessible for your users too. Not sure what do you mean by automation.
To be simple. Imagine you have a project in Blynk. The whole project with all the functionality will be in your app. It's very similar to sharing, but it's your app + features like WiFi provisioning