I have a new site selling a few hundred items done with Zen cart, my question is do i need new content regularly to get higher rankings and traffic. By new content i dont mean new products, i am adding new stuff every week, but articles related to my site?
That, really, is up to you. If you are adding new products, etc. every week, then Google will see your site as updated and fresh. If you want to add articles because you think it will make your site stand apart from competitors, then you should. After all, adding some informative content (instead of just a bunch of sales pages) may tell visitors that you're a legitimate, honest business, instead of someone just out to make a buck. Question for you - do the products on your site come with product descriptions from the manufacturer? If so, then your site could be filled with duplicate content, and you don't even know it.
Well, that is a question that will have varying and debatable opinions. Because it is a retail website, putting too much textual content can drive people away and increase your bounce rate. Sure, content is KEY and you have to find ways to include it into your site. However make sure the content is QUALITY content. I suggest that you perhaps add a blog attached to your site, and write articles regarding different products you want to push. After posting these articles on your blog or your site (if you have a section for them) you can then submit to directories with a link back to your site. You can also include a product reviews section, as well as custosmer satisfaction opinions which you control which ones get published. You can also optimize your meta tags and your H1. Both have lots of value when being crawled by a SE bot. Also add alt text to your product pictures. Remember that SE bots are "blind" they do not see pictures. Therefore you have to tell them what is in that particular picture.
You could always start a blog and then you could freely post updates and new articles whenever you needed. Maybe even release a coupon code on the blog to get people to check it out more than once or twice. You could even use the blog to have customers sign up for a newsletter and begin your list building.
Fresh content always helps although that is not the only factor for SEO. Links to your sites, sitemaps, meta tags etc. all play into this. Still it is certainly worth adding new articles directly or via a blog. At the end of the day you need to cover all the bases so the googlebots can make an 'educated' decision on how to rank you.
If you're looking for higher rankings, you need to know what keywords you want to rank for and get backlinks with those keywords used as anchor text. Adding new content to your site will help Google visit your site regularly and index those updates, but backlinks are the best way to change your rankings.