Game guide for TCP/IP play in Heroes 3.

No. Using the second method, you can play without a modem. You just need to know the IP address.

So, as I understand it, I won't be able to use the first method, but I can play using the second (universal) method?

And regarding the IP address, that's not a problem if I use the Hamachi program (without it, my IP address in the game is 12.13.14.15).