Firstly reasons that can cause the CAD to increase are-:
1) Changes in Australia's terms of trade- If these deteriorate then Australia must sell more exports in order to purchase the same amount of imports.
2) A fluctuating exchange rate- An increase in the value of the Australian dollar will encourage more imports and discourage exports.
3) The level of economic activity within Australia- When there is a high level of economic growth being experienced there will be high levels of consumption and investment. The increases in these areas spill over into the trade sector, resulting in an increase in imports.
4) The level of economic activity in Australia's trading partners- The level of exports will be influenced by the economic activity in the countries that buy Australia's exports. When I hear this I think of the demand for Australian commodities by China, in particular gas.
5) Increases in net foreign debt- when this increases, the interest payments on the debt increase. The interest payments are recorded in the current account and add to the deficit.
Practically, if you learn the structure of the Balance of Payments and the components of the CAD in particular, you'll pick up what can impact upon it.
Secondly, do unemployment and inflation affect the CAD?
Well if Australian inflation levels are higher than its trading partners, exports will be less competitive and imports more attractive.
Regarding unemployment, if labour, a scarce resource, is not being utilised fully, economic growth is not at its optimum. This therefore impacts upon our international competitiveness.