These are difficult concepts to fully understand. I will try to explain but I'm not sure if I will be successful:
1) "imagining": "imagine" is a better fit here. With words like "imagine", "think", "mean", "expect" followed by a clause (subject > verb), we usually use the present tense.
So: "I imagine / think / mean / expect that I will try again tomorrow."
2) "meaning" This is like in 1). You write, "Well, perhaps I'm not meaning that exactly." "That" in this sentence refers to "I'm beginning to feel lonely." So it's the same pattern: "I don't mean that (I feel lonely) exactly."
3) "settle" Here "am settling" fits better. It's an action that still continues. If you say "I settle ..." it sounds like a habitual action, like "I drink a glass of milk before I go to bed." But if you're still doing it, you say, "I'm drinking a glass of milk."
4) "seeming" This should be "I seem" because similar to 1) it's setting up the next verb: "I seem to be spending" or "I seem to spend". And it's a habitual action: you ride the bus often.
5) "think of" Here, "I'm thinking of" is right. Why? Isn't it setting up the next verb: "moving" like in 1)? Haha, yes, but "of moving" is continuous so "I think of moving" sounds like a habitual action, something you do often. But in fact, it's something you continue to do: you are still thinking of moving. If you said, "I think I'll move nearer to college" that would be fine.
6) "knocks" If you were writing it while it happened, you would say, "someone is knocking." But if you wrote after the interruption was over, you'd write, "someone knocked." "Someone knocks" is a habitual action – not what you were describing here.
7) "has a party" Again, "has a party" sounds habitual, like she has one every weekend. But you are talking about one party, so even if it's in the future, you should say, "is having a party."
8) "expecting" This is exactly like 1): it should be "I expect you'll get..."