I am in need to do some testing in 2013 QA Site Collection but the 2013 QA Site Collection is not in SYNC with the 2013 PROD Site Collection. Is there any easy way to do that without making the PROD site ready only during office hours.

The PROD site has custom workflows and InfoPath forms so what is the best approach and please mention the steps.

1. Backup-SPSite -Identity "site collection url" -Path "backup file path"
Restore-SPSite -Identity "site collection url" -Path "backup file path"

2. Export-SPWeb [-Identity] "site url or GUID" -Path "backup file path"
Import-SPWeb [-Identity] "site url or GUID" -Path "backup file path"

3. DB Detach/Attach
Would this method change the PROD url to QA automatically as the urls are different once the detach attach is done.

Please advise