1. In libs/options.php is where you can edit the minimum length for titles and other things.
2. If you are familiar with phpMyAdmin you can go into the links table and where you see link_summary, edit that to be text and not varchar. this will allow you to increase the limit to something higher than 255. We have fixed this for future builds here
http://svn.sourceforge.net/viewvc/pl...v&revision=179
3. I'm not sure off the top of my head the best way to limit the full description. There might be a way to limit the number of characters a textarea can use by editing the form in submit_step_2.tpl