... Gutters... Are required to have a downspout every 20 ft, or two on each end of 40 ft pieces... Slope should be 1/8th of an inch for every piece up to 10 feet.. Which shouldn't be very obvious. My employer has me install hangars every 16". The gutter looks like it needs another couple hangars on the end, or the fascia is crooked... If the fascia is crooked you will likely need to replace soffit and have your fascias redone...
They "dutch lapped" the edge which is to *layer shingles*... which gives it the bumpy layered look to the shingles.. *cough* hacks *cough*... That waviness of the roof deck is caused by sheathing... If its really messed up, installing a sufficient amount of 2x4 backing and re-sheathing that gable end should work. However, I am curious to see what the fascia looks like on the poorly shingled end...
Old, rotted fascias, buckling and shifting might be the major cause of your problems...

:)