For first problem, you could look at:
http://home.mnet-online.de/willybilly/fdhelp-internet/en/hhstndrd/base/callver.htm
Invalid opcode, means your CPU have encountered an unknown instruction.
So it depends on your CPU versus what the program request.
In QEMU, -cpu pentium-2 ... or other can be used to change the emulated CPU.
On real hardware... more harder to change CPU.
Although I found the following link:
https://groups.google.com/g/alt.os.free-dos/c/JDN8xIJ_ikg
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