I'm new to Trello and have a couple of questions

[Sandy Larowe]

1- Once somebody is an Observer or a Member and assigned to a card, do the automatically get updates when something changes?

2- How do I send the link to the team (Members and Observers) of my Trello Board OR are they automatically linked to in when they sign up with Trello with my invitation?  Do they have to create a password?

[Tymek Zapała]

Hello to the community @Sandy Larowe ,

1. Yes, card members will get an notification for due dates, mentions and other card updates. As or due dates notification, remember to fill "set due date" reminder field in the Dates section, or it will not send the notification. You can learn more exactly what notifications are send here.
2. To invite new members to your board, click "Share" button in the right top corner of the screen, locate "Share this board with a link" text and click "Create link" under it. You can now send this link to other people. Yes, they will have to create a password because they need to be Trello users to access your board as members/observers.