FYI about the account number on checks. Years ago when I was in college, I had a summer job working for the payments processing group at a bank. Basically opening up envelopes & typing in amounts paid, etc. Sometimes the check & invoice with it were separated. We would find checks all by themselves sitting on the floor sometimes. Those checks with account numbers would be credited, those checks without account numbers had to be destroyed.
So while it's certainly not required, it's a good idea to put account numbers on your checks.