You can use same title and description for directory submission, but you can use different targeted keywords and description for better result.
For me, each day I change my description but not title. I don't like the same description again and again in various website. However, I keep title same but not always. If I have 5 keywords than I rotate the title time to time.
Of course you can, you can also use a keyword for your title.. Also, you can do a variation for your title too
Yes you can use same title in different-2 directories . That title name must be your keyword & your ranking will increase, that much back-link you site will get.
Well if you're just starting out in this field then yea use one keyword or 3 keywords to promote your site and make sure to push those keywords as far as possible when you start ranking for them, its time to go after more keywords