Go ahead, get 'em. Screw 'em on and go for it.

At the very least you will have established sizes to go off of for the correct fit.

The parts are probably worth $60 in general, it's not possible for us to tell you how much of the package would do you any good in particular.

You might be able to use some of them, but there might not be one of them that will work for you. Remember, the cranks are wrong.

At this point, it's your choice.