"5 . the action is in the future. Correct? So it means, Julie will be buying her ticket to New York next month."
'be going to…" is Present Continuous Tense. Look at the difference between that, and Future Continuous Tense:
where D =decided to buy a ticket to New York
NOW = the very moment of speaking these words
B = buying the ticket.
Can you see that the action in the Present Continuous Tense begins BEFORE NOW, and continues into the future.
Future Continuous Tense:
…NOW|>…...will be buying…>B|…
Can you see that the action has NOT BEGUN. It will start and end at some time in the future.
For 5, the first verb form was correct; but you then chose 'has saved', which is Present Perfect:
where S = begins saving.
PP only takes us up to NOW, the moment of speaking; so we can't use a future time expression such as 'by then'.
You corrected this to 'will have saved by then'.
Sorry - 6 was fine. I should have written 4,5 and 7.
So have another look at 4.
7 is now correct : "Why are you smelling the meat? Do you think it's off?
(But still, watch capitalisation and punctuation.) You corrected it to:
" why are you smelling the meat. Do you think it's off?
If I am not too tired, I might go to the party.
If I wasn't so tired, I would go to the party.
If I hadn't been so tired, I____ to the party.