What exactly is the capital structure of an organization? Additionally, what do we mean by the cost of capital?

Respond to the following in a minimum of 175 words. Remember to in-text cite and then reference materials where required

Discuss the Following in a Single Initial Reply: 

1) What exactly is the capital structure of an organization? Additionally, what do we mean by the cost of capital? When considering capital projects, are there ways of measuring risks and costs associated?

2) While there are different types of stock issued in organizations – for now, let us focus on the most common in organizations – common stock. Who can define what common stock is and provide us with some specific characteristics associated?

3) When considering common stock, what is meant by the value of a share? Is it the book value of a share as calculated based on the financials, or are we thinking of market value? Is there is difference?