No, in VirtualBox virtual CPUs are not simulated. CPU emulation is terribly inefficient, a modern OS would be unusable on an emulated CPU. Your CPU actually has built-in support for virtualization, ie. running code as if it wasn't a virtual machine, but in an environment controlled by host's code. So when you're setting how many cores are available to the VM,...
No, that's not possible.
Outgoing connections go from your router, whose IP is dictated by the internet
supplier (ISP), so is not something that you can change.
The 10 IP addresses you purchased allow outsiders to reach you in 10 different ways,
and so allow your server to distinguish between 10 different types of requests.
This way you can setup 10 websites ...