Go with the skimmer especially if you have trees, catches the leaves before they hit the bottom.
Decide if you want a koi pond, goldie pond or water feature, there is a big difference on filtration. I can pm you the koi site I mod on, excellent construction site. If this is your first pond, it helps to know what you need to do. If you want fish, you'll need mechanical and biofiltration. Alot can be done as DIY to save some money. Learn by our mistakes.