Which sump return pump?

[TheCureForSin]

Went on a little spending spree on setting up a sump. Trying to figure out which pump I'm going to need to use as a return.

I'm going to lay my sump out similar to this: (bought that)
http://cgi.ebay.com/ws/eBayISAPI.dll...TODAY.m238.lVI

So it'll be Lifereef overflow box down to that ^, then up from that (about 4' from bottom of sump to top of tank), into a SCWD, then to 2 U Tube returns.

One thing I'm wondering, is it ok if I have 1" tubing coming into the sump then 3/4" back to the tank? The SCWD uses 3/4" so one of my questions.

Any other tips? how much room to leave in the skimmer area or anything else?

The Sump is a 20L also