Start with the brushes then the course matting getting finer then the rock, if you wanted better bacteria swap the rock for k1 and use an air pump to move it around.
Size of pump realy depends on size of pond and how much flow your filter can take and what fish you are keeping if koi you should turn over the hole pond every 2 to 3 hours and yes it must be on 24/7
Filter and pump should realy be work out at same time so they match pond size and if you are pumping up hill as head hight on the pump will change pump raiting quite alot.