First things first. You in the states or canada? That can make the difference as far as where to go order from.

Ive seen crab apples flower here in east and west facing walls, just not as prolific as full sun. You coudl try to graft a branch or two of another variety on the apple you purchase to save space.

Type in " apple pollination chart" in google and you get a few. A general rule i always hear is an apple that flowers at the same time, should pollinate your tree.

#3 is a yes, I have a crab on the east side, it gets morning sun, and late afternoon, it gets the late afternoon because the crab foliage is above the roof line, and it blossoms a lot. I think if it got 4 hours of sun, it would still blossom.

I'm not sure if pruning a standard apple tree to maintain short manageable height is really doable. You'd have to lop the top of the tree off several times per year to keep it down low enough, and it would be a lot of work. It should work, if you want to try it. But personally I wouldn't.

Looks like Cummins has got a few trees left. http://www.cumminsnursery.com/available2012.php

Also Maple Valley. http://maplevalleyorchards.com/Pages/Apple_Trees.aspx

And Raintree still has a few. http://www.raintreenursery.com/Apples-Pears/

I don't know much about crabapples except that they bloom like crazy in general. I'm just starting to grow my own now this spring. I'm betting yours will be fine.

Here's a link to the best pollination chart I have found online to date. It doesn't have everything but it should give you some idea. http://www.acnursery.com/apple_pollinizer.pdf

Thanks, I'm in the US (Southern WI). Sounds like I should reconcile myself to a big tree if I buy a standard, then. I guess that wouldn't be the end of the world, since it would take a decade or more to get really big.

Bob,
Even trees on semi-dwarf rootstocks can get pretty large.
The catalogs tend to say things like, "semi-dwarf: 12-15 ft tall and wide"(and that's if you prune!) - have you thought about how BIG that is?
Taller than the roof of your average 1-story home, wider than your living room?
Ed Laivo, at DWN used to say something like: "Standard apple tree - will become as large as an apartment complex, please purchase separate property."
Yes, 'standards' ultimately become larger - but they also take longer to come into bearing than do the dwarfs/semi-dwarfs.

Bob,

Like other pointed out. A standard size tree can take 7-8 years to fruit. Even if you buy a 3-4 years old tree, you still have to wait (and pay more).

I have a semi-dwarf Williams Pride apple that fruited in 2nd year. I personally like this vareity very much because it tastes good and is disease resistant.

I'd suggest you check Adams County Nursery. When you open its web page, click on Order Fruit Tree. A list of fruit varieties will show. You'd check out the Disease Resistant section. There are a number of very good disease resistant apple varieties to choose from. They sell bare root trees but like I said, you probably could get fruit in 3 years. It maybe even faster than buying a standard, older tree that you still have to manage to get it smaller.

Even if you don't buy bare root tree from ACN, you will have a better idea what varieties are more disease resistant.

ACN is one of the many reputable nurseries people on this forum recommend. Good luck.

Thanks - I did not realize that standard trees took so much longer to fruit. I'll definitely go dwarf, then.

Check out Miller's Nurseries in NY. They have a large selection of dwarf, ultra dwarf and comspurs. I purchased 8 trees from them two years ago and have been very pleased with the quality. I researched which type of apple trees would be suited to my region by using the local university's extension service website. Also, I would recommend using the Japanese apple bagging method for your trees - - I tried it last year and it really does work.