I can't personally vouch for the AmazonBasics one you posted (I think it may be more of a USB hub than a USB charging adapter). It seems to mention that the ports aren't powerful enough to charge tablets, which may show its lack of power.

I can, however, highly recommend the Anker line of multi-USB port chargers. Here's the one I have. It's on sale for $14.99. 5 USB ports, all perfectly functional for charging any device, including tablets.

http://www.amazon.com/Anker-Desktop-Charger-Technology-Smartphones/dp/B00DVH62J2

Is there a reason we wouldn't want the 25W one here for $15.99?

It says all five ports charge Android at normal speed.

15ft is pretty long, I don't see any with really good reviews. There is a cable matters one on Amazon that has decent reviews, but that's pretty much it.

Anything over 10ft is really too long for a passive USB cable, you will probably need an active one and I don't think anyone makes active micro-usb cables.

Your best option is probably something like this combined with a 10ft cable.

Edit: Also definitely don't go with a cheap Chinese cable from Ebay. Something like this is pushing the limits of USB and needs to be made of high quality components.