Sick tree? Please read...link to pics posted

I've got some pictures of a tree in our backyard posted here http://michaelelliott3.tripod.com/tree/tree.html
Thanks to anyone who can shed some light on this; I'm a complete tree non-expert. I don't even know what species it is. At the end of last summer, we noticed some strange growths or tumors on the ends of the twigs. I recall that I broke a couple of them open, and there was a liquid inside which was bluish in color. This year, I see these small greenish balls forming along the green shoots. The abnormal-appearing ones seem to be present at the junction between the leaves and the twig. There are some smaller ones that also look like normal fruit/seeds from the tree (they are on their own individual stalks). There are also some growths on many of the leaves. I've included close-ups of the front and back of the leaves. The lesions penetrate through the leaf. I've looked on the 'net a bit, and the only thing that I can find is "black knot gall" which sounds similar.
If anyone can write back to me at snipped-for-privacy@aol.com (subject: trees) and let me know, I'd appreciate it. We're in mid-Oklahoma, if that helps the species/disease determination. The main info I'm looking for is:
1) what species of tree is this?
2) do you know what is going on? For all I know, these are normal findings
3) Any ideas about what to do about it?
Thanks! Michael
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(subject: trees)

The tree you have is a Hackberry. The fruits on the tree will turn red and ripen later. The fruits are edible.
I checked around a little and found this web site: http://insects.tamu.edu/fieldguide/aimg92.html
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Exactly right I think! Thanks Elizabeth and Roy. I've noticed the little flies collecting on the plastic slide under the tree. (Although I thought they were supposed to comeout in the fall).
But that leaves the other lesions...which look like black knot gall I guess.
Thanks everyone, and if anyone has suggestions, let me know
Michael
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