Question

1. He has lived in the city for 10 years.
2. He lived in the city for 10 years.
3. He has gone to LA.
3-1. He went to LA and he lives there now.

(Are they all grammatical? Does #3 mean 3-1?)

4. He went to LA, but soon came back.
5. He went to LA, but soon he came back.
6. He went to LA, but he soon came back.
7. He went to LA, but he came back soon.
8. He went to LA, but came back soon.
(Which ones are grammatical and commonly used?)

Answer 1

1 - 4 are all grammatical. 3 doesn't necessarily mean that he now lives in L.A. Maybe he's just gone to L.A. for the afternoon.

4 - 8 are all grammatical and are commonly used.