Thanks for the testing, looks like Spirit Surge doesn't have a damage bonus on top of its other bonuses. I suspect Spirit Link is actually 0CE/0VE, which is what I suspect Reward is too.
I think all Pet commands might really have infinite range. It does seem that monsters need to be within a certain radius of the target in order to receive them though. For instance, if I have movement speed on BST and I run up to a monster (outdistance my pet) and give the "Fight" command, my pet doesn't attack it if it was too far behind me when I gave the order.
There has already been testing on Lancer's Vambraces +2, I think, if that helps to guide you:
https://www.bg-wiki.com/bg/Lancer%27s_Vambraces_%2B2