Learn English – This summer on our city is very hot or This summer is very hot in our city

Here are some search results from the Corpus of Contemporary American English (COCA):

  12464     thank you very much
  16        thank you in advance
  0         thank you very much in advance
  0         thank you in advance very much

As you can see, thank you very much is a common collocation. Thank you in advance is attested but less common, and the other combinations have no results whatsoever.

Ideally, you wouldn't combine in advance with thank you very much at all; it's simply not idiomatic. But if you do, I think it sounds marginally less unnatural putting in advance at the end, perhaps because thank you very much is such a common collocation, and breaking it up with in advance is odd.

So if I were forced to pick, I'd pick thank you very much in advance, although my real preference is for neither.

"Not only" can be moved to the beginning of the clause for emphasis. It is then followed by auxiliary verb+subject. If there is no other auxiliary, "do"is used. "But" can be left out in this case. Examples:

1. Not only has she been late three times, she has also done no work.

2. Not only do they need clothing, but they are also short of water.

Your second sentence, as mentioned by Fantasier, is correct.