Yes, it helps in building links, these are the best sites you can get one way links. In my opinion you should get listed, but it's up to you to decide whether you need backlinks from so and so site.
its not so necessary to have your site listed in dmoz. its only an advantage, if your site isnt listed in it, dont worry...focus on other link building strategies.
if you can get your site listed, then go ahead and have it listed. DMOS is not what it used to be years back. ethical standards of DMOZ editors have been questioned many times and from what i can see, it is extremely difficult to get a site listed in DMOZ unless you personally know an editor (or figure out how to bribe one). with that being said, it doesn't hurt submitting.
I had 2 websites, 1 was indexed on Dmoz and the other wasn't, not difference - actually the one that wasnt indexed on Dmoz ranked higher!
Every bit helps, but it can be tough to get accepted into DMOZ, and the review process takes a very long time generally.
Before sometime ago,Google built their own directory (Almost cached from DMOZ), so it no longer helps you in imporving your SEO rank however if you are listed their, the value (Selling value, ad value) of your site increase much..
Google gives priority to the site which is listed in dmoz and yahoo directory. Try to suggest your site to dmoz it is free of cost but read out first their terms and conditions if you fulfil the conditions then you should submit, it will take a long time to be reviewed your site at dmoz.
It's better to be listed than not, but don't lose sleep over it. DMOZ doesn't carry as much weight as it perhaps used to.
It is important for yourpage rank tooYou cna check these websites too: http://indexhttp.com/2011/11/20/special-seo-service/ +http://www.1buy.info/top_backlinks.html
What a joke! What's the difference from a DMOZ link on a New site or Old site? Nobody bothers with DMOZ anymore and NO it's not required.