Org mode timestamp format when exported

Instead of patching org-translate-time, you can remove brackets by adding the following function to org-export-filter-timestamp-functions:

(defun org-export-filter-timestamp-remove-brackets (timestamp backend info)
  "removes relevant brackets from a timestamp"
  (cond
   ((org-export-derived-backend-p backend 'latex)
    (replace-regexp-in-string "[<>]\\|[][]" "" timestamp))
   ((org-export-derived-backend-p backend 'html)
    (replace-regexp-in-string "&[lg]t;\\|[][]" "" timestamp))))

(eval-after-load 'ox '(add-to-list
                       'org-export-filter-timestamp-functions
                       'org-export-filter-timestamp-remove-brackets))

See http://endlessparentheses.com/better-time-stamps-in-org-export.html for more details.

Try this:

(let ((org-time-stamp-custom-formats
       '("<%A, %B %d, %Y>" . "<%A, %B %d, %Y %H:%M>"))
      (org-display-custom-times 't))
  (org-latex-export-to-latex))

Upd.: If you want to remove brackets <> from output string, you have to patch the function org-translate-time. Normal behaviour:

(let ((org-time-stamp-custom-formats
       '("<%A, %B %d, %Y>" . "<%A, %B %d, %Y %H:%M>"))
      (org-display-custom-times 't))
  (org-translate-time "<2014-04-29 Tu.>")) => "<Tuesday, April 29, 2014>"

With patched function like here https://gist.github.com/boykov/11387660

(let ((org-time-stamp-custom-formats
       '("<%A, %B %d, %Y>" . "<%A, %B %d, %Y %H:%M>"))
      (org-display-custom-times 't))
  (org-translate-time "<2014-04-29 Tu.>")) => "Tuesday, April 29, 2014"

The brackets <> are hardcoded in the function org-translate-time and you can't remove their by fixing org-time-stamp-custom-formats only.