REPOST: Two PHP Questions

Sorry, My Mail server crashed, so mail was boncing right after i sent this. Here we go again! Hello! My first question deals with writing a PHP file to write a PHP file. Do i need to take any precations when writing <? or ?>, because thoes actions will take place inside the <? and ?> of the php file that is doing the writing? Second, is there anyway to run a php file from a cron job or the command line? Thanks.