You can install kitchen storage cabinets yourself if you are comfortable with the process. It may take longer and require tools you will need to buy, but installing them yourself may save lots of money.
You should install kitchen cabinets in the kitchen most likely. If they are floor cabinets you should install them against a wall on the floor under a sink or counter. If they are wall cabinets you...
You can rip out your old ones and put in new ones that may be a different design that allows for more storage. Or, you could see if it possible to add on to your current ones.
In order to install the kitchen cabinets you should probably ask someone who has done it before to help you. Otherwise the place where you bought the panels from have instructions in the box.
That depends on the quality and number of the cabinets, any additional trim pieces, the condition of the floor and walls, hardware installation, and so on. Multiple pieced crown and under-cabinet...