It is a personal choice. We cannot say which is better than other one. It depends what is our financial requirement and status. Are we looking for high returns or safe returns?  Are we looking for long term gains or short time profits? So depending on these factors the choice depends. Stocks will always be bit on risky side at it depends on market conditions which are governed by  numerous factors.

Working capital is that part of the business capital which is available for the day to day working activities of the company. These are the fund which are available for the operational part of the business. This is the actual liquidity available to any business or entity.

Yes depreciation is the loss in the value of the fixed asset due to its daily wear and tear. Any asset which is used and even if not used has some corrosion in its value. This decrease in value is know as depreciation.

If the right kind of investment is done in stock market then in the long run the return on investment is very high as compared with other sources returns.