The USB "standard" charge rate is 500mA, but that can vary quite a bit either way. 2700 mAh/500mA = 5.4 hours. This is an approximation. Your actual results will vary. 1 Watt = 1Volt Amp, so 2W/6V = .333 A, or 333mA. 2700mAh/333mA = 8.1 hours to charge. Again, this is theoretical max. Lots of things affect actual charge times (like a few clouds
Extending the cable (within reason) on the solar panel will not impact performance. Extending it a foot or two is fine. Extending it 100 feet is not a good idea.