QuoteAlso say you have to use a 47 uf Cap-how much does voltage level play into it? I've seen some 47uf caps at differing voltages.
The voltage level needed is determined by how much power you are putting into the pedal. So if you're using a 9 volt battery or power supply, you'd be fine with a 16v. However it's usually safer to go a bit higher in case you want to add more voltage for more headroom. I think the standard that most guys use for pedals are either 25v or 50v, but keep in mind that 50v caps are larger than 25v caps.
The Futurlec grabs bags are great for stocking your bench early on for cheap. I'd recommend getting the 1/4 watt resistor pack, the ceramic cap pack, the electrolytic cap pack, the mylar cap pack, the multilayer ceramic cap pack and the led pack. As for the other packs, you'd be better off ordering transistors, ICs and diodes as you need them because you don't get many useful parts for pedal building. Also, keep in mind that it takes a long time for your order to reach you (took about 3 weeks for an order I placed to reach Seattle) and that you get the same values in every pack, so ordering multiples of the same pack isn't really useful. Here's the link for the value packs: Futurlec Value Packs.