Correct. However, this rarely happened. Contributors are not supposed rename files, and they can indicate deletions and additions in plain English (I typically request a tarfile for additions).
Further, it can not handle e.g. things like the executable bit or similar things that SVN otherwise does manage. That is what makes a patch only partially suitable.
Probably correct; this isn't a problem in practice, either. In fact, it is better if properties come from the subversion installation of the committer, rather than from the contributor, as the committer is supposed to have his autoprops set correctly.
I do think that "svn diff" will record property changes, and that may include svn:executable. I don't know which patch tool would interpret them, though.