Yes. When you click the Use the template button, you'll be taken to Softr studio and can start working on the template. If you don't have a Softr account, you'll be prompted to register first. A free account will have all the functionality you need to get started, and you won’t be asked for a credit card.
Yes, there's a 30-day free trial available for all the paid plans, and there's also a "forever free" plan that gives you access to key features to build and iterate.
You’ll be prompted to connect your data source during onboarding or if you start from a template. In other cases, go to your "Application Settings" and navigate to "Data Sources." Next, click "Connect a Data Source" and select from the list.