if the rims are of different depths, then your spokes will probably not work unless its deeper, in which case you will have to add new threads and adjust the length, which requires a spoke threading tool. The cheapest one is a hozan, which is about 150 dollars. Single butted spokes usually are around 75 cents per, and double butted around 1.25. Double butted spokes build into lighter and stronger wheels. I recommend linseed oil as an inexpensive spoke prep. You will need a truing stand, here is a list of DIY ones. http://bikehacks.com/5-diy-truing-stands/
You will also need spoke wrenches. (6 bucks or so). Sheldon browns website has a bunch of instructions on how to build wheel. Considering it sounds like you have no idea what youre doing, it would probably come out pretty bad. Its easy to learn how to build a wheel, but it takes practice to learn how to build them well. Take it to a shop.
In regards to risers, look for clamp diameter of the bar (25.4, 26.0, 31.8, etc etc) and make sure it corresponds to the stem.