We are developing custom blockchain from scratch. Could some please help me with the audit process?

Our chain is PoSv3, are any known type of attacks dangerous?
Is the Virtual Machine completely isolated from the base chain?
Is the (actual) block time creation stable? Must simulate for many years forward.
Is there any weak point (for example, network threats) that an attacker can exploit gaining control of the node? Or force it to shutdown easily?
Any bugs that will be found must be reported.

Any suggestions? Please let me know.