For your second question, try this as a starting point:
%%%
\version "2.19.80"
get-layout-header = #(define-scheme-function (score)
(ly:score?)
(let* ((output-defs (ly:score-output-defs score))
(header (ly:module->alist
(ly:score-header score)))
(title (assoc-get 'title header))
(composer (assoc-get 'composer header))
;; Look for sym in all output definitions
;; is there a way to determine of which
type an output definition is?
(get-sym (lambda (sym)
(car (filter (lambda (el)
(not (null? el)))
(map (lambda
(output-def)
(ly:output-def-lookup output-def sym))
output-defs)))))
(indent (get-sym 'indent)))
(display indent)
(newline)
(display title)
(newline)
(display composer)))