Could you possibly post a picture of the area the tree is intended for?

In my opinion, deciduous bushes make poor foundation plants, especially on the corner of your house where usually some kind of evergreen 'anchor' is called for. Situated next to an evergreen plant of the same size, a deciduous bush looks like a missing tooth in winter. To help out the situation you can plant an evergreen groundcover below it and and evergreen tree above it. Do you have room? A picture would sure help.
Korean Lilacs have just a short time in bloom and the winter branching pattern leaves a lot to be desired. I'm sure your landscaper can come up with a better plant to fit your situation.
I'm near Seattle with a completely different climate, so I'm not going to suggest any plants for you, just general principles.
Mike

I am an (extreme) novice at gardening/planting/anything involving things that grow.

==>>> well then lets start by splainin a few things to lucy ...

no 'tree' goes 4 feet from the house..

nothing you list is a tree .. they are all flowering shrubs.. on standards.. [thats the trunk part] ... repeatedly pruned TO LOOK like a little tree ... read that: perpetual yearly maintenance ...

i am frankly of the opinion that foundation plantings.. are planted to HIDE the foundation.. NOT 'ON' THE FOUNDATION ...

and my experience in owning many houses.. is that it is IMPORTANT.. to have AT LEAST.. a 3 foot bare spot between the house and the closest edge of anything planted ... most of us.. paint houses.. use ladders to clean gutters.. wash windows.. hang xmas lights .... store hoses.. all kinds of reasons to have space there ...

so if your 'landscaper' had any clue.. your design would probably be shifted out.. at least 4 to 6 feet.. to allow for this space i am talking about ...

i too.. would like to see a picture of the area.. see link ...

otherwise.. it would be nice to know the house color.. the color of other plantings.. etc ... in other words.. what color flower would 'fit' into the rest of the plan ...

ken

Here is a link that might be useful: how to post pix

Those three suggested are within the parameters. Others include:
Rose of Sharon (Hibiscus syriacus)
Seven Sons Flower (Heptacodium miconioides)

Dax

As Ken says, you've got to be able to get between the tree and the house with enough room to move, pull weeds, paint, use the spigot, play hide-and-seek; four feet isn't enough room unless the tree never gets wider. You also have to leave enough room that the canopy of the mature tree isn't shoved up against the house, which is not good for either the tree or the house.
When you're planning, imagine a column as wide and tall as the mature tree will be, and place that column with the outside edge a couple of feet from the house; now put your new tree in the center of the column, and hope it's not in the middle of your driveway.
I have two peegee hydrangeas in my front yard; they are about 100 years old (yes, really), and the canopies are at least 12 feet x 12 feet; the bushes/trees are about 15 feet tall. That's what you've got to plan for, and it seems to me that most landscapers (around here, anyway) plan and plant for immediate results, not leaving room for anything to mature, so the homeowner has got to start cutting things down a couple of years later. [In their defense, I would guess that many homeowners demand immediate results, so that's what the landscapers give them]

Your zone is either 4 or 5 depending upon where you are in the state. There may be a tiny, tiny area in extreme SE Iowa right along the Miss. River that is 6a.

I would also suggest that you stay with something dwarf and possibly evergreen or nearly so. Cotoneaster is often grown as a weeping standard, stays quite small, and bears red fall/winter berries. That might work for you. I would check out good local nurseries and see what they have that would be slow-growing and stay small. My sister used to live across the street from me, after she sold out, the new people planted a Cornus kousa and a pussy willow in the two foot wide foundation beds between the house and sidewalk. Of course, it was a really dumb thing to do, but the house went through a number of owners and was finally foreclosed and left vacant a couple of years. The new people that bought it for a song under $100K, which was about a sixth of what my sister sold it for in the mid 1990s, had the sense to remove them.

Now, mind you, I have done similar crimes. I just planted a pair of small arborvitae about 2 feet out from the back of my house. But, I consider them disposable, I know in a few years I will either have to move them or cut them down. I just wanted something quick and cheap to screen some utility access in an area that nothing ever does that well, and these fit the bill. For what I paid for them, if I get 2 good years out of them I'd be happy.

Here is a link that might be useful: Updated USDA Zone Map for 2012