My understanding is that short story collections by unknown authors are extremely unlikely to be picked up by publishers. When people buy short story collections, they tend to buy collections that are themed (and often edited by a Big Name) or collections by their favorite author.
So, if you're going the short story route, you'll probably want to look at publications (print or online), contests (be careful of scams) and anthologies. These are ways to build your name as a short story writer.
However, being a short story doesn't often mean anything for novel writing. It may help, but it's more likely that it doesn't mean anything really. (Says the woman with over fifty short stories in more than seventeen different publications.) Your novel will STILL have to sell itself.
Write on!