Automatically assign numbers

Automatically assign numbers

1. I know to assign the numbers but how to get numbers to change automatically with next new record. I keep getting the same number in field.
 
2. My [Next] button does not go to next form. It goes to a default page and I have to log in again. I am unfamiliar with writing deluge script.
 
3. On customer form I want to begin typing in Customer name (say last name) and have dropdown list show up or if name is the only one, have all information show up.