1) Allows me to upload my products in bulk, (via csv file or suchlike).
2) Has default front-end product display as one item per row, rather than the usual grid format.
3) Allows me to create my own product attributes (i.e. different from the typical 'size', 'condition' and 'color' that most carts provide).
4) Is suitable for an inventory of about 5,000 unique products, under 250 categories.
5) Has a responsive front-end, suitable for viewing on desktops and mobiles.
I have been looking at Megento, but wonder if there are other free ones, with a supportive community, that fit my above requirements. I don't want to pay a monthly subscription, or pay a programmer to get it up and running, if I can avoid it, as I'm a new entrepreneur, strapped for cash.
Thank you kindly for any help/suggestions...