1) The way you did it will work great. The results will be similar to a 10 minute addition and then cooling the wort rapidly.
2) Adding cold water is also fine. Cold distilled or RO will generally give the best results especially for extract brews. It doesn't have any added minerals and the process ensures that the bacterial content is insignificant. But I've had fine results with cold tap water and tasted beers that came out fine with spring water.
3) instead of oranges try a couple of ounces of coriander seeds in the boil. You can normally find it fairly inexpensive at Indian markets. The flavor holds up better during fermentation than orange peels, and much better than juice or pulp which, despite any stabilization attempts, ends up tasting a little rotten in my experience. There is a hoegarrden clone recipe on my blog and in my book.