Can't comment on the 7300, but I have heard the 7200 with 4 RTi28's and the CSi30, it sounded very sweet. As for speaker wire go to Home Depot. They have 12 ga speaker wire in bulk for 34 cents a foot by me. Maybe +/- a few cents/ft depending on where you are in the country. Alot of people use it.
So, you're considering the CSi40 over the CSi30, good choice!