If you wait for Beta - you'll have to pay for the monthly subscription. In Alpha it is all included (as well as the beta) from what I have read. Also if you get the top pack you can send out free beta invites to your mates too! IMO - Get Alpha!
Beta is being treated essentially as a soft-launch so a reset/wipe is not expected for the Official Release and whatever you create will remain in some form or fashion.
Novaquark has stated they are planning an upgrade to the planet after Beta that may require some constructs to be removed, but they will be returned to you in the form of "magic blueprints" with everything included and will allow you to respawn your constructs as soon as the server is restarted.
