What do these mean?
1. It's Jay calling from work, I would like to take a day off tommorow. (How does the comma change the sentence?)
2. It's Jay calling from work, and I would like to take a day off tommorow. (How does 'end' change the sentence?)
3. It's Jay calling from work. I would like to take a day off tommorow. (How does the period change the sentence?)
4. It's Jay calling from work; I would like to take a day off tommorow. (How does the semi-colon change the sentence?)

What do these mean?
5. How does the 'end' change the sentence? (Is this correct? How come it sounds kind of odd?)
6. How does 'end' change the sentence? (Is this correct? Why don't I need an determiner here and it doesn't sound odd at all?)