Technical issues with Heroes III.

Thanks, is there a way to bypass the 16-bit limitation, because it's annoying to constantly switch?

If someone could suggest a solution, I'd be very grateful! Because switching is really annoying, so I have to play in 16-bit mode. And that's a pain... But I think it's probably impossible... Although I hope I'm wrong.

And one more thing: my game resolution is 800*600, which looks very small on my 1280*1024 monitor. Is it possible to increase the game image without changing the monitor's resolution?

The game is already 800x600. And regarding increasing the image, it's probably not possible.
However, there is a way, although it's a bit clunky. In the monitor settings, you can stretch and compress the image. It's not ideal, but it will increase the image size :D