Lisa, my hat is tipped to you. I imagine that you could handle this job if, IF you have the right equipment.
power washing sends up a flag to me. Power washing is a good thing, but if done with too much power or in the wrong manner, you can cause more troubles than you already have.
I would suggest you rent a power washer around 2000 psi's and with a FAN tip. Do not stay in one spot too long spraying and always stay away from windows and doors or eve vents. Always spray downward and not upward. You do not want water shot up into the works of the walls for later rotting.
You will need a good extension ladder and one that you will feel comfortable standing on while power spraying. Get used to the torque of the wand on level ground before you attempt the height of a ladder.
Once you have knocked off all the debris and junk, then mend the siding as you need. Buy a bundle of cedar shakes and use only zinc or galv, nails for fasteners. These will not leave those rust running marks.
Lisa, the next step is too rent a spray rig or buy a waggner spray gun. If the job is not too small, this inexpensive tool will do the job. It will take longer, but it may be more user friendly for you than a big rig.
Lisa, this is my opinion and others may disagree, but I feel that your stain/paint must be sprayed on. The surface is too rough and rigidty for hand painting.
I would recommend a product from Sherwin William's called Woodscapes. it comes in as many colors as you want and is water based. I really like it. If you have not painted/stained your siding in a while, this job could and will soak up alot of paint. Be ready for a big purchase in stain/paint.