Using whistle to teach "come"

I have a few questions. I want to use a whistle when outside, to teach "come". I see too many people saying, "come here!, come here!" over and over to their dogs, and I can see that first of all, their tone of voice is always changing, from normal to frustration, and secondly, the command means less when they repeat over and over. So I think I will start with a whistle and see how that goes. Ok, now for the questions.

1) Would you recommend a regular "gym" whistle, or a silent dog whistle?

2) I dog can understand that two commands mean the same thing, right? Example, using a whistle and saying "come" means the same thing. Wouldn't want to have to use a whistle in the house all the time, lol

3) I plan to use a clicker for most of the dogs training. WOuld you use the whistle AND clicker when training, or leave the clicker out, for that one part of training? If you would use it, how? Blow whistle, once the dog comes, click and reward?? I am afraid that may cause confusion.