Query against a view vs. query against the underlying base table
It depends on the construction of the view. SELECTing from a view with NOLOCK or READUNCOMMITTED table hints should avoid blocking the underlying tables (with the risks that entails).

Indexed views (SQL Server term - more generally called materialized views) actually are stored on disk separately from their underlying tables, and are updated as the underlying tables are updated. This not only consumes more disk space, but can lead to contentions and delays if the underlying tables are frequently modified. SELECTing from the view can still block updates to the tables underneath, since when those tables are updated, the index for the view is also updated.

And, as you thought, SELECTing from a normal view can temporarily block queries that are changing the underlying tables, just like SELECTing from the tbles directly can.