Both are standard items, although power cords are somewhat pricey. Generally 25 or 30 feet is plenty.
This place has pretty much anything you would want, but isn't always the least expensive. You can check walmart too.
http://www.campingworld.com/
They also have brick and mortar stores all over the country. There's one in Fort Worth.
Sewer Hose:
There are LOTS of options, and they get fancy. This one is relatively inexpensive and will get the job done:
http://www.campingworld.com/shopping...-hose-10/27862
25 foot power cord:
http://www.campingworld.com/shopping...r-light/102413
30 foot power cord:
http://www.campingworld.com/shopping...r-light/102414
Notice the type of plug on the trailer end (female end of the power cord), and make sure your trailer has that sort of connector (twist-lock type). The male end of that cord is the standard 30 amp connector used in campgrounds.