Basic Midi Interface Setup Question, Need advice on midi interface Options

[yojames]

Hello all,
I'm learning Logic Pro one step at a time. I've been working very nicely with my M-Audio Solo recording live instruments. I now have a midi controller, an Akai USB/MIDI pad controller, and a midi string sound module. My question is; do I only need a single midi in/out interface for the sound module and run the other two controllers via USB? Or do I run all three through a midi interface that will handle 2 ins and 1 out (at least). The manuals fail to address such basic questions. I'm using Logic Pro 7, and an iMac G5.
Thanks!
Also, any advice on which midi interface to take a look at would be helpful as well.

James