I aksed this same question myself recently (just built a 9x14x2.5)
http://www.woosworld.net/pond/

and in the end I decided to build them both in to make my future life
easier, neither of them was very hard but my skimmer is already
proving itself worthwhile, removing alot of floating debris.

When the water warms up I am going to check on my bottom drain, it
doesn't seem to work as well as I hoped - I still have dirt on the
bottom of the pond. (This may be because it's not installed correctly,
I'll have to see)

As for your pump, mins is only a 1.25 opening, and you can see the
waterfall it is pushing (about 35' of 2" pipe with a 6-7' height raise
gives me something like 11-12 head height)