There's a ton of information in the pond section, so I would browse through there and check out the options. Additionally, we actually just helped out a guy who bought a new house and discovered a pond with koi in it in the backyard! He basically had to start from the very beginning. So that thread might be very helpful for you. here's the link:
http://www.aquariacentral.com/forums/showthread.php?t=106281
As for the shade issue, probably a good idea would be to add some floating live, fast-growing pond plants or even fake lilypads to the pond. That would create a shaded area in the pond. Fast-growing plants are a good idea because goldfish like salad, so plants that reproduce quickly and often are essential. Or, you could try your hand at building a shade for the pond yourself.
http://www.aquariacentral.com/forums/showthread.php?t=106281
As for the shade issue, probably a good idea would be to add some floating live, fast-growing pond plants or even fake lilypads to the pond. That would create a shaded area in the pond. Fast-growing plants are a good idea because goldfish like salad, so plants that reproduce quickly and often are essential. Or, you could try your hand at building a shade for the pond yourself.