No, all of those sites don't rely on a voting system and you retain all rights. A site like Threadless.com, on the other hand, actually puts your design to a vote, then they retain certain unlimited rights to reproduce the "winning" design because they take on the risk of actually silkscreening, belt printing, embossing or embroidering the final design. Their policies may be acceptable to a person struggling for recognition, but for others it is unreasonable to yield those ownership rights.
Also, I'd recommend starting the process of building your store(s) online, then buy a domain later with the name you want that redirects to your online store. That way, it won't matter which site hosts your designs.
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