I think most people put 7 pin plugs on the driver's side of the bed between the wheel hump and front of the bed about half way up. I don't have a particular harness in mind, but something that makes it easy for your particular truck would be a good choice.
tweetys.com usually has the cheapest prices, but etrailer.com and amazon.com sometimes have good deals. For tie downs, you should also try used at ebay.com and craigslist.org. The torklift.com site will tell you fits your vehicle and has install instructions and videos.