1. The bank took longer to clear the check because it would have to send the check back to the bank where the check was first drawn, this is what we call float.. your credit union probably had a system in place that gives you a temporary "credit" until that check officially clears.. this is all pretty much null and void after 9/11, most banks can just send an image of the check eliminating your float.
2. you're two other points are mute really, you can find banks with similar advantageous pricing structures; the advantages of credit unions are they don't have to pay the outrageous taxes federal banks are paying, this helps keep their lending rates down, the important thing to remember though is a credit union is not an FDIC insured thing, if it goes under you're screwed. the nice thing is, its hard for a community driven thing to go under, but if all the lenders start short selling good luck.