my test result regarding 2) on latest 4.1.13:
%<U --- not work, will simply leave U in log file
%U equal to %>U, the final request URI.
test env:
.htaccess:
RewriteRule abc.html test.php
when access 127.0.0.1/abc.html?c=3&d=5, the log for "%r" %<U %U %>U is:
"GET /abc.html?c=3&d=5...