I'm quite new to ZenCart, currently working on setting up our own site.
-My Point Of Sale system will export my store inventory into an Excel document. Columns I choose are model/upc, name, description, price and inventory count.
-I then set up the easy-populate add-on and modified one of the templates given into an excel document to show the columns I wanted. Used this as my master populate list and made a back-up copy. I also added another column with the formula that allowed me to take the UPC/Model name and add .jpg
-Easy Populate is quite daunting as most of this all is to new users, ask lots of questions but figure out the solution for yourself. Without understanding thru application, you might as well pay for a web developer to maintain your site.
All I do is export my list every Friday from my POS and feed the information into my columns one after the other. I populate my list to show only items in stock, because of my image formula I don't need to worry about the images not matching up or broken links, just make sure all your images are .jpg, .gif or whatever you decide.