Please keep your questions to one theme per thread. Your original question was about errors calling a script. Now you want to know some basic RM techniques, that have nothing at all to do with the script. Putting them together into the same topic is confusing, as what you are asking now has nothing to do with the title of the thread, and nothing to do with scripts.
I will move this to VX Ace Support now, only because you have posted so many screenshots. Next time you have a question though, once it's answered, please mark it as solved so the thread can be closed, and ask any new, unrelated questions in a new thread.
This also helps others who might have similar questions - if they were searching for help on making NPCs do different things based on conditions, this thread might come up, but they'd never think to look at it because the thread title has nothing to do with NPC behaviour or conditions.