virtualbox.org

I am quite new to virtualization and just started to play a bit with virtualbox.
The idea is to utilize a powerful machine with multiple VMs and provide these for instance to an audience attending a technical training.
I made a first trial, but I found already an issue, which seems to make this approach not reasonable:
One of the tools, I am normally using and would need to demo, recognizes network devices by their MAC address using a proprietary discovery protocol below L3. This works properly on the host but not in the VM, probably due to NAT. Could this be solved by bridging the VM NIC with the host NIC? Would it be possible to have multiple VMs on the same host and all using the bridging in parallel via the physical host NIC?
Sorry if these questions appear to be silly, but as I said, I have very limited knowledge about virtualization.....

Would it be possible to have multiple VMs on the same host and all using the bridging in parallel via the physical host NIC?

Yes. Have you tried it yet?

Yes, I just tried it and it seems to work as expected.
One question: Are there any known limitations how many VMs can physically share a host NIC (aside of CPU power and RAM, of course)? I am thinking of something in the range of 10 to 15 VMs on one host. I do not have a host yet which would be powerful enough for that to test it, but I am considering to apply for the necessary budget and I need some confidence before I do so.
Thanks for any information about this subject!

The only consideration is what will the router support and the host. You need to have enough memory, both storage and RAM to support all of the guests and enough CPU power and cores. Keep in mind that the host will need some resource no matter what so do not exceed what the host can support and leave some available to it.