Discuss the issue with the person you hired. Probably you will have to forfit the deposit. It just depends on the situation and how far into the job the individual is.
That depends. Many security companines use contracts to ensure that they are repaid what they install + be gauranteed an income. For example ADT will install a system for free or a $99 activation...
All the thinks that give good look to your home like sofas,beds,table,dining table and many more did not help you in improving the price of your home but it improves your home in terms of lifestyle.
Yes, if both of the parties agree to the cancellation. Yes, if there are terms and conditions that permit either party to back out. And there is always the option of arbitration or of litigation.