6 sentences from Vince (advanced grammar issue) help needed...

OK, here it comes, some heavy stuff...

1. That must be the end of the first part of the performance. What happens/is happening now.

Which one would you choose? The key says that "happens" is OK but I don't have the foggiest idea why...

2. transformation: I'm finding it really enjoyable to work here.

The key says: I'm really enjoying working here. Again, I don't know why and why I cannot use "I really enjoy sorking here"

3. transformation: I take work home regularly because of my new responsibility at work.

The key says: My new responsibility at work means I take work home regularly. Why is that? and why not this one:  My new responsibility means TAKING work home regularly. ?

4. Is there any difference between "I look forward to hearing from you" and "I'm looking forward to hearing from you" ?

5. Is this sentence OK? : Are you hearing from Wendy these days? The key says that it's wrong and a correction is given: Do you hear... and I don't understand why

6. Can I say "I'm suspecting (her)" ? and how is it different from "I suspect (np. her)

7. Are "How do you feel?" and "How are you feeling" the same in meaning?

thanks in advance... hope someone will answer me...

best wishes!