Emacs -- How to extract all elements of a list - emacs

Question

I am looking for some assistance, please, to extract all elements of a list of files and/or directories that have been marked in dired-mode. Essentially, if there were some way to just remove the parentheses from around the result of (mapcar (lambda (filename) (file-name-nondirectory filename)) (dired-get-marked-files)), then that would do the trick.
(start-process
"name-of-process"
"*output-buffer*"
"/usr/bin/zip"
"zip-file-name.zip"
(mapcar
(lambda (filename) (file-name-nondirectory filename))
(dired-get-marked-files)) )
The result I am seeking will look like this:
(start-process
"name-of-process"
"*output-buffer*"
"/usr/bin/zip"
"zip-file-name.zip"
"filename-number-one"
"filename-number-two"
"filename-number-three" )
EDIT:
The start-process function does not generally accept a single concatenated string of arguments. Instead, each argument must be separately spelled out (with quotation marks around each argument), or the argument can be a variable.
Here is the debugger message from the first example above -- the error occurs because there is a parentheses around the file names -- i.e., it cannot be a list.
Debugger entered--Lisp error: (wrong-type-argument stringp ("file-name-number-one" "file-name-number-two" "file-name-number-three"))
start-process("name-of-process" "*output-buffer*" "/usr/bin/zip" "zip-file-name.zip" ("file-name-number-one" "file-name-number-two" "file-name-number-three"))
eval((start-process "name-of-process" "*output-buffer*" "/usr/bin/zip" "zip-file-name.zip" (mapcar (lambda (filename) (file-name-nondirectory filename)) (dired-get-marked-files))) nil)
(cons (eval exp lexical-binding) values)
(setq values (cons (eval exp lexical-binding) values))
(let ((debug-on-error old-value)) (setq values (cons (eval exp lexical-binding) values)) (setq new-value debug-on-error))
(let ((old-value (make-symbol "t")) new-value) (let ((debug-on-error old-value)) (setq values (cons (eval exp lexical-binding) values)) (setq new-value debug-on-error)) (if (eq old-value new-value) nil (setq debug-on-error new-value)))
(if (null eval-expression-debug-on-error) (setq values (cons (eval exp lexical-binding) values)) (let ((old-value (make-symbol "t")) new-value) (let ((debug-on-error old-value)) (setq values (cons (eval exp lexical-binding) values)) (setq new-value debug-on-error)) (if (eq old-value new-value) nil (setq debug-on-error new-value))))
(let ((exp (if exp exp (read--expression "Eval: ")))) (if (null eval-expression-debug-on-error) (setq values (cons (eval exp lexical-binding) values)) (let ((old-value (make-symbol "t")) new-value) (let ((debug-on-error old-value)) (setq values (cons (eval exp lexical-binding) values)) (setq new-value debug-on-error)) (if (eq old-value new-value) nil (setq debug-on-error new-value)))) (let ((print-length (and (not (= 0 (prefix-numeric-value insert-value))) eval-expression-print-length)) (print-level (and (not (= 0 (prefix-numeric-value insert-value))) eval-expression-print-level)) (deactivate-mark)) (if insert-value (with-no-warnings (let ((standard-output (current-buffer))) (prog1 (prin1 (car values)) (if (= 0 ...) (progn ...))))) (prog1 (prin1 (car values) t) (let ((str (eval-expression-print-format ...))) (if str (princ str t)))))))
(if (active-minibuffer-window) nil (let ((exp (if exp exp (read--expression "Eval: ")))) (if (null eval-expression-debug-on-error) (setq values (cons (eval exp lexical-binding) values)) (let ((old-value (make-symbol "t")) new-value) (let ((debug-on-error old-value)) (setq values (cons (eval exp lexical-binding) values)) (setq new-value debug-on-error)) (if (eq old-value new-value) nil (setq debug-on-error new-value)))) (let ((print-length (and (not (= 0 ...)) eval-expression-print-length)) (print-level (and (not (= 0 ...)) eval-expression-print-level)) (deactivate-mark)) (if insert-value (with-no-warnings (let ((standard-output ...)) (prog1 (prin1 ...) (if ... ...)))) (prog1 (prin1 (car values) t) (let ((str ...)) (if str (princ str t))))))))
lawlist-eval-expression()
funcall-interactively(lawlist-eval-expression)
call-interactively(lawlist-eval-expression nil nil)
command-execute(lawlist-eval-expression)

Answer 1

What you want is to use apply with (mapcar ...) as its last argument:
(apply 'start-process
"name-of-process"
"*output-buffer*"
"/usr/bin/zip"
"zip-file-name.zip"
(mapcar #'file-name-nondirectory (dired-get-marked-files)))
Note that (mapcar #'function list) is a shorter spelling of (mapcar (lambda (arg) (function arg)) list).

Answer 2

combine-and-quote-strings is what you want:
(combine-and-quote-strings (mapcar (lambda (x)
(file-name-nondirectory x))
(dired-get-marked-files)))
EDIT: the following will give you a single, quoted string with internal quotes. Not sure if it'll play nicely with start-process:
(mapconcat
(lambda (x)
(concat "\"" (file-name-nondirectory x) "\""))
(dired-get-marked-files) " ")
EDIT: Righty-o, let's try this. Splice the backquoted list with ,#, then eval the whole thing:
(eval `(start-process
"name-of-process"
"*output-buffer*"
"/usr/bin/zip"
"zip-file-name.zip"
,#(mapcar
(lambda (x)
(file-name-nondirectory x))
(dired-get-marked-files))))