The first method that you outline is correct.

31.91% = 68.09% to 31.91% = 2.1333 to 1

The methods that I know of to calculate the odds of making one's hand with the next card:

1. Divide the number of unknown cards by the number of outs that you have

2. Subtract one from the result

e.g. For your example...

47 / 15 = 3.1333
3.1333 - 1 = 2.1333

The odds of making your hand are 2.1333 to 1.

Alternatively:

1. Subtract the number of outs that you have from the number of unknown cards

2. Divide the result by the number of outs that you have

e.g. For your example...

47 - 15 = 32
32 / 15 = 2.1333

The odds of making your hand are 2.1333 to 1.

Either way works, it's just up to your personal preference.

Your calculation for working out pot odds is correct.

A $14 pot with a $4 call to you gives pot odds of 3.5 to 1.