yea not really sure what you are asking but before you start an ecommerce site, research the niche which you want to do business. If you want to rank organically, you want to see the difficulty to rank for each one of those keywords to basically understand how challenging it would be to get up there.
When i was doing eCommerce seo last time, i spent lot of time in finding high search volume and low competition keywords using long tail pro and keyword shitter which is a free tool and got many product levell keywords, which were easy to rank and traffic got doubled in just 4 months time.
I am using Long Tail Platinum, its awesome.
Its always do 70-80% of my keyword research.
Thats more likely what I was lookin for. Thank you, Honey!)
Depending on necessity. I do affiliate marketing, so I always go with some Review Keyword, Product Keyword, some Keywords for Articles & some sub category keywords.How many keywords you choose to work on?