Quote 4
It seems to me that the further East you go the more unpunctual are the trains. What ought they to be in China? (1.5)
Throughout the novel, Bram Stoker is obsessed with train travel and other "modern" inventions for transportation and communication. So it's important to notice that in this first mention of train travel, it's to compare the "East" unfavorably with the "West."
Quote 5
"How dare you touch him, any of you? How dare you cast eyes on him when I had forbidden it? Back, I tell you all! This man belongs to me! Beware how you meddle with him, or you'll have to deal with me." (3.34)
Dracula doesn't try to hide that he's in control, does he? He actually claims ownership of Jonathan.
Quote 6
Lucy has not walked much in her sleep the last week, but there is an odd concentration about her which I do not understand; even in her sleep she seems to be watching me. She tries the door, and finding it locked, goes about the room searching for the key. (6.41)
Lucy's passivity while she's sleepwalking makes her easy for Dracula to control.