Is there maybe a way to selective select special nodes, i.e. either corner nodes or smooth nodes?
For example, I would like to select all corner nodes (or smooth nodes) and delete them. Converting into a smooth/corner node is not what I want.
I hoped that with find (Ctrl+F) you could also select special nodes. Maybe there is another way?

The find command is not node specific, only object and group specific. if you open the xml you will see that the type of node (c, s, a, z) is stored separately from the handle and node coordinates which are all in one line. Since ctrl-f really is just reading through the xml file it can't be given anything to search for that will select a node or set of nodes. You can for example select every object that has any smooth nodes, or even change all smooth nodes to symmetric nodes but you can't select nodes to delete them with ctrl-f