Bardic Luck & general rules clarification

[Ragnarookie]

So when it says immediately, just to be fair gm, can one assume an appropriate response time is like 2 seconds. And not actually take their sweet time reading everything?

So I can carry unlimited small items and I can carry items that are not my race or class I just can’t use them but is open to trade.

Can cheat or hireling’s cheat be used on a stead?
Also the big rule, so if I have a big steed by itself I can’t carry or equip anything else big?