You're mixing regular expressions and regular strings.
Try these:
;; square brackets - escape the first one so you don't get a [..] regexp
(font-lock-add-keywords nil '(("\\(\\[.*]\\)"
1 font-lock-keyword-face prepend)))
;; parentheses - don't escape the parentheses you want to match!
(font-lock-add-keywords nil '(("\\((.*)\\)"
1 font-lock-keyword-face prepend)))
;; quotes - single escape so you don't break your string:
(font-lock-add-keywords nil '(("\\(\".*\"\\)"
1 font-lock-keyword-face prepend)))
;; other characters - not regexps, so don't escape them:
(font-lock-add-keywords nil '(("\\('.*'\\)"
1 font-lock-keyword-face prepend)))
(font-lock-add-keywords nil '(("\\(<.*>\\)"
1 font-lock-keyword-face prepend)))