Since you are in Springfield I recommend that you go to Bass Pro and look at the various units that they have. Ask questions and have them demonstrate the functions of various units. Today's units are pretty complicated if you get into structure scanning.
For me a good gps is a must so that I can pinpoint cover and return to it time and time again. For that reason I run 2 gps units with that are connected via nmea 2000 network and ethernet cables.
As for transducer mounting if you have a fiberglass boat mount the stern one inside the bilge area. Put the bow unit's transducer on the trolling motor.
If I weren't going to have 2 units, mine would be at the bow as that is where I spend hours and only minutes at the helm. I have a 20' boat and for years ran one unit at the bow with 2 switched transducers.