EBay (EBAY) is no longer the young upstart with a fresh approach to the auction block. Yet it does have one key unit that's changing how Americans pay for things. PayPal, a wholly owned unit of eBay, now holds 1.1% of global payments market share. That can surge to 2.8% by 2022, says Susquehanna Financial Group. That would propel deal dollars to $939 billion from the current $150 billion. That's the impact of rising share of a growing market. The