1)Without knowing where you are located it is impossible to answer all your questions. In Canada there is a limit on the number of outlets and lights on any one circuit. Other places in the world have different limits and ways of calculating them. Knowing your location will also determine what year of code you need to adhere to, whether a permit is required or if you are even allowed to do your own electrical work. Your city, state (province) is close enough for a location.
2)Stapling wires is not required if the wire is fished through a finished wall.
3)More junction boxes (and the resulting splices) are often just more possible trouble spots.
4) A project like this is reasonable easy enough for a first project. Take your time and neatness counts. Ask questions.
Can you also tell us what type of wiring is existing that you want to reuse? It may be well worth your while to replace it.
2)Stapling wires is not required if the wire is fished through a finished wall.
3)More junction boxes (and the resulting splices) are often just more possible trouble spots.
4) A project like this is reasonable easy enough for a first project. Take your time and neatness counts. Ask questions.
Can you also tell us what type of wiring is existing that you want to reuse? It may be well worth your while to replace it.