Lion/Mountain Lion Mission Control used with CTRL+# (10.6 Spaces-like) Is there a way to still use Control+# (e.g. Control+1, Control+2, ...) to switch to a particular Desktop? In Spaces' parlance: to a particular Space? I have difficulties swiping the trackpad and could use the old shortcut?

Also: Could I configure a particular App to open in a particular Desktop number, like in Snow Leopard?
In Lion, by default, will switch to a particular Desktop if you hit Control+Desktop's Number. Go to System Preferences / Keyboard / Shortcuts / Mission Control and check if you've overwritten this shortcut. 

Yes, you can configure a particular App to open in a particular Desktop. To do so just:


Navigate to that particular Desktop.
Open the App you want to assign, if its already not on the Dock, and right click on it.
A contextual menú will show up. Under Options you'll see a submenu called Assign to and three different options. All Desktops, This Desktop or None. Select This Desktop.