Re: no spoke wheels??
yes it is normal but 7 speed freewheels are getting harder to find as 8,9, and 10 (and even more) are more prominent. They're still out there though.
The thread is a right hand thread so when you pedal it tightens and when you coast it freewheels so it won't unscew. In fact sometimes they're hard to get off even w/ the right tool. The newer style is a freewheel hub (f/w is on the hub) and the cluster is called a cassette. These types slide onto the cogs of the hub f/w and are individually interchangeable so that you can set up the perfect gearing for your app.