My sister lives in West Chicago (and works at Fermilab). She's got one pineapple growing in a pot. She got it though the winter under a lamp. I think it's more about staying warm and photoperiod than anything else.
Avocado seeds are not true. There's a good chance the plant will not make fruit that is the same as the fruit the seed came from. But, they are fun to grow in a glass as a houseplant anyway.
When I find an avocado tree that I really like, I just remember where it is and go back to pick when it's in season. Avocado, mango, guava, papaya, lilikoi (passion fruit) grow wild all over Puna and are free for the taking.
I have cloned avocado trees by air-layer. That works well.
Can't really comment on the apple-flower trick. Never had to try it. I'm not much of an apple fan. Never lived where they grow (until now). There are some apple orchards here, up at about 6000ft. elevation on Mauna Kea. Those who have tried them say they are very tasty.