Yeah there are Type A and Type B avocados, from Wikipedia:
There are two flowering types, "A" and "B". "A" cultivar flowers open as female on the morning of the first day and close in late morning or early afternoon. Then they open as male in the afternoon of the second day. "B" varieties open as female on the afternoon of the first day, close in late afternoon and reopen as male the following morning.
I've read that avocado trees from seed are really unpredictable when it comes to the fruit, it could be nothing like the parent, or fruit very poorly, etc. They take many years to fruit as well. I don't think any of the dwarf varieties fruit very well like dwarf citrus or other dwarf trees though. Avocados are probably just a pipe dream for me though.
I really need to get a greenhouse like that though. I would have it full in no time. There are so many tropical or sub tropical fruits I want to grow that I can't because of my stupid climate.
I do have dwarf Meyer Lemon, Kumquat, Fig trees though. There are so many others I want to grow though, bhudda's hand citron, mangoes, lychee, etc.
But anyway, I'll stop thread hijacking now. I should probably just move to southern Florida. :o