Never mind. You wouldn't be the first one to post in the wrong category, nor will you be the last.
Wall cavity insulation is best done by professionals because of the danger of wires and pipes. They are also a lot faster and overall it will probably work out cheaper than doing it yourself. Pros' detection equipment will show up anything in the wall and they will know all the shortcuts.
The ceiling depends on what is there now. Squashed (settled) insulation is less effective as it doesn't 'trap' the warm air so removal of the old stuff is advised. This too is an harrowing and dangerous (fibreglass dust) job best done by experts. Some stuff had asbestos in it.