iVentoy and Ventoy are two completely different software, but both come from the same author.
Please install the VC++ runtime library for VS2019 firstly. Microsoft Official Download Link
Yes! Please refer About Secure Boot
Yes! Please refer About Third-Party DHCP Server
Yes! Please refer: Example Network Topology Diagram
Yes! Please refer: Example Network Topology Diagram
The client and iVentoy can be in the same LAN/VLAN or in different LANs/VLANs. Please refer: Example Network Topology Diagram