Cs-Cart Mv Copy To Testing Server And Backup

Currently we are working on the production version of the platform and since it is about to launch, we want to copy the whole system to another server that will server for testing purposes.
Thus, I have some questions regarding this:

1. Is there a proper way to do it?

2. Is it better to outsource some kind of service to perform this task?

If yes then who would you suggest and how much would it cost?

3. The front-end of the our platform is highly customized and is not a theme. Will we experience issues because of this?

4. If it is possible to make a complete copy of current system, will we experience issues with setting it up on a testing server?

5. Since our system is highly customized we will live any issues with backups?

Version is 4.12.2.SP2 - Multi-Vendor

Please take a look