Do you currently have any other poultry? Chickens perhaps?
Im thinking of buying 2 ducks but if I just bought 1 would that be ok? - People do this, but it's not ideal. There's a large time commitment in having just one duck instead of two since you'll have a duck that is likely to imprint on you. If you're looking at outdoor ducks get at least two. Ducks are flock animals and need to be in a group.
I have a yard that is fenced and I also have a tool shed that I'm thinking of keeping my ducks in. Are there any renovations I would need to do in order to keep the ducks healthy? Ducks will make a mess of what ever you keep them in. If you want to have them make a mess of your tool shed, then this will work as long as it's secure from predators.
I live in Colorado so I was just wondering would I be able to keep them indoors for weeks at a time when it gets cold in the winter and hot in the summer? - again, ducks are messy. Many breeds of duck are fine in cold climates as long as you bring them fresh water to replace the frozen water.
I'm thinking about imprinting the ducks. Is this a good idea for a noob duck owner? - this is personal. I don't like that people do it. It makes your duck VERY dependent on you emotionally. When you leave, the duck will cry. Every. Time. People that get one duck want this but you need to be able to be with the duck close to 24/7.
It's possible to have a relationship with your ducks with out imprinting, you just have to spend time with them and not be discouraged when they are afraid of you (which will happen.)
What is the time commitment? - outdoor ducks? Depends. I spend about 3 hrs a week if I do the bare minimum. Indoor ducks? I can't comment.
How much would it cost for 2 ducks yearly? - If there's no vet care needed then it's just he cost of water and food. How much food you need to buy is going to depend on the breed and how much they can forage in your yard.