I have dismantled existing wall,cleaned off old mortar and going to rebuild it.I am starting two rows above the original footing which is in fine condition. I have 60 - 4" cinder blocks and 10 - 4" half blocks. Do I just buy premix bags of mortar mix for this amount of work? And also with pilasters at each end of this 12' long wall I am rebuilding do I start at either end. One end is where the 4 backyards come together and then the next portion is the wall being built towards the front of the house separating my next door neighbor and myself.