Version 2008 does NOT over-write Version 16 or any earlier version. So, you can use them both.
Not sure what the issue is on the Location information. That is "I used name, date township, County, then the state". What is the issue.
Yes, Version 2008 wants to Add USA. You can look at the Place Name Authority page, (location) and you can resolve any of the location issues that might be there. You will also notice that 2008 does not automatically provide County and Township words or abbreviations.