that’s the default Logitech software, it’s not the one from the link. The link is an old program that allow you to modify the keybind on your controller, however I’m not sure whether IMC allow this or not, since you are modifying the game file.
I just come across some post a while ago that mention an addon call mount them good or something, you can try to search for it, seems like it can allow you to mount your pet even If it’s far away.
IIRC you can create a new account on steam with the gmail, then verify it again, it should work, as I had create a gmail account for this purpose before, since my steam account is using ymail.
the pet AI had been bugged for quite some time, the only way to let it became active again, is by changing channel / relog the char.
if not mistaken, pet exp gain is depend on your char, you need to be grinding mob that is close to your char level (not sure what the max difference is), but just by questing + grinding normally it should be able to level up.
stamina isn’t really important unless your char is a mounted class or pet user.