1 - is there a guide of how to use WHDLoad - an example of how to install a random game
No guide needed, it is a simple concept. There is a single command file called WHDLoad that goes to the c: directory. Then you download install packages from whdload.de and just run the installer and have the original disk handy to insert when requested. No cracked/pirate copies will not work.
After it is installed you have a game that is HD installed. You then use Tooltypes to configure the game for things like PAL/NTSC/CPU Caches/NoFast/Quit key assignment.