With regards to the UI issues - can you confirm that you are using the current official release Q2 2009? Are you able to reproduce the layout problems you describe on the editor's online demos available here:
As far as Safari producing DIVs instead of Ps - we have logged this feature for implementation for the coming Q3 2009. At present there is no way to "tell" the underlyign Safari rich-edit engine to produce Ps. One way you can try to workaround the functionality would be by attaching to the OnClientSubmit
method of RadEditor, obtaining a reference to the editor's content area and replacing all DIV's with Ps, e.g.
<telerik:RadEditor OnClientSubmit = "OnClientSubmit" ../>
var doc = editor.get_document();
var divs = doc.getElementsByTagName("DIV");
//TODO: Run a cycle and replace all DIV elements to Ps, or do something more fine-tuned.
the Telerik team