Hi Redi,
I get your hardiness zone as 5.
http://www.gardenweb.com/zones/zip.cgi
I do want to clarify one point you made.* You said a tree of 20' tall but 30" in diameter.* Did you mean a 30" diameter trunk at maturity or a crown of 30' wide?* I'm thinking you meant 30' wide crown.
You mention the list of trees with 'rapid growth'.* Most trees that grow slowly are softwood trees and tend to be short lived.* Hardwoods grow more slowly and live longer.* It is generally considered that we plant trees for our grandchildren.* With that said, there are some lovely trees that will do well in your location.
I consider a low maintenance tree one that is planted in the right place so it stays healthy and matures to fit the space so it doesn't need pruning to fit.* Trees that don't shed alot of litter with seeds, seed pods, fruit or small branches that break often and don't have large surface roots are also on that list.*
The damage to the trunk of the tree could have been from a weed trimmer or lawn mower.* A proper mulch ring should help to avoid that problem.* I'll give you a link to show you how to do that.* The ants could have been carpenter ants or another type of ant that is associated with aphids or scale pests.*
With all that said, here's some small ornamental trees that would work for you.
Crabapple - Malus hybrids - get one with the smaller apples as it leaves behind less mess and the birds find the smaller apples easier to eat.* They're about the size of cherries.
http://www.ag.ndsu.edu/trees/handbook/th-3-75.pdf
Eastern redbud - Cercis canadensis - native tree in pinkish/lavender or white.* Birds gobble up the berries.
http://www.urbanext.uiuc.edu/treesel...fm?PlantID=195
Dogwood - Cornus florida (native in white, pink or red) which flowers before the leaves appear.* Birds gobble up the berries.
http://www.urbanext.uiuc.edu/treesel...fm?PlantID=592
Kousa dogwood - Cornus kousa - not native and flowers later in spring with the leaves.* Birds gobble up the berries.
http://www.urbanext.uiuc.edu/treesel...fm?PlantID=199
Star magnolia - Magnolia stellata - lovely fragrant white or pink flowers before the leaves appear. Probably better to select the later flowering variety in your zone.
http://www.urbanext.uiuc.edu/treesel...fm?PlantID=229
This site is from the University of Illinois Extension Service and should be helpful with selections.* The more attributes you check off the less selections you will get.
http://www.urbanext.uiuc.edu/treeselector/search.cfm
This site is out of Florida and may not have all the trees you find listed, but has lots of info on trees about litter, mature size, surface roots, etc.
http://hort.ifas.ufl.edu/trees/index.htm
Depending on where you purchase your tree, most nurseries will plant it for you.* It usually costs as much as the tree for that.* If you decide to plant yourself here's info on how.* The first site is a video.
http://www.arborday.org/trees/video/howtoplant.cfm
http://www.ext.nodak.edu/extpubs/pla...ees/f1147w.htm
http://www.ext.colostate.edu/pubs/ga...7833.html#post
http://www.treesaregood.com/treecare/mulching.aspx
http://www.watersaver.org/pdfs/FALL_..._FOR_TREES.pdf
More info you should find helpful.
http://edis.ifas.ufl.edu/MG089
http://edis.ifas.ufl.edu/WO017
http://www.ext.colostate.edu/pubs/Garden/02926.html
http://www.treesaregood.com/treecare/trees_turf.aspx
Newt
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.