How to limit the maximum length of the title of a node?
Try Maxlength module to do this.


  Maxlength allows you to set maximum length of any field on any form
  making use of the form API. This includes fields created using the UI.
  (Example: any text field on a node) In D6 Maxlength allows you to set
  maximum lengths to the body, title and CCK textfields of any content
  type (node).
  
  When the maximum length is enforced for a field, while editing content
  of that type some Java Script will countdown how many characters are
  left, also if the Javascript is turned off, it falls back to form API
  validation.


Automatic Nodetitles : I haven't try this. Try once, hope this module solve your issue.


  "auto_nodetitle" is a small and efficient module that allows hiding of
  the content title field in the form. To prevent empty content title
  fields one can configure it to generate the title by a given pattern.