Sentences check please

Hi, everyone

Would you take a look of the following sentences for me?

"(1)The photos we took last time have already been developed. (2)Those are all our happy memories. I've prepared one album for you and one for Peter. However, since Peter has flied back to Canada, I'm just thinking to airmail the photos back to him. Do you have his home address that I can use for posting?"

- For the 1st sentence, is the word "developed" with the photos used correctly here?

- For the 2nd sentence, is the meaing is complete and sounds natural in Eng? What I want to say is, we had a good time that day and I treasured much.

- For the sentence, "since Peter has flied back to Canada..." Is it right to use the word flied here? or it's better to use gone ?

- For my last sentence, I think that it's bit too long. Is doesn't sound natural? How do I write in a better way? Do you have any advise?

Thank you very much!