Dear teachers,

Would you please correct my exercise ?

A trip to Florida
Tomorrow I (1 leave) am leaving for my holiday. I (2 take) am taking the 14.20 flight from Gatwick for Orlando, Florida. When I (3 be) am in Florida, I (4 do) shall do / am going to do (both possible?) lots of sightseeing. Of course, I (5 arrange + already) have already arranged to visit Disney World. I (6 be) shall be / am to be / am going to be there on Friday – three days from now.
So, by 15.00 hours tomorrow, I (7 fly) shall / will be flying over the Atlantic. The plane (8 cruise) will be cruising at about 40,000 feet. All the passengers (9 watch) will be watching the in-flight film, or perhaps we (10 eat) will be eating. The flight (11 take) takes exactly six hours, so by 19.30 (that’s 7.30 in the evening) we (12 travel) will have travelled for more than five hours and I think maybe we (13 modal + see) would have been able to see America already. By 20.30, we (14 arrive) will have arrived.

[by here means before or at ?]

Apart from Disneyland, I have decided that I (15a) am going to visit a famous Florida dolphinarium and (15b) see the trained dolphins. And I (16 have) have a cousin in Miami, so I (17 spend) am going to spend the weekend with him and his family. He (18 promise) promised / has promised that we (19 visit) would visit the famous Everglades, where I assume I (20 see) will see crocodiles – or is it alligators? Finally, on the day before my return, I (21 have) will have lunch with the famous American crime writer, Elmore Leonard, though how this is possible is a story in itself!
In all, I (22 stay) will be staying for ten days. So by this time next week, I (23 spend) will have spent at least a thousand pounds! I (24 return) shall return with several rolls of film for developing because I (25 take) am going to take photos everywhere I go, and I (26 use) am not going to use my digital camera.

[is for correct here?]

Thank you very much for your help.