Not sure what your questions are. The building plan is useful but lacks showing the character of the property. It would be nice to know the general location/climate. Photos?

Based on what i see I can only make guesses. Tell me how close I am.

The land has only a slight slope, nothing steep. The high corner in the graphic is at the lower left, the low corner at the upper right. The septic lines extend a lot more than the approximate 30 ft drawn and tend to follow the contours.

It's a large flat lot,pretty leveled. The setbacks slope down for drainage.
I just don't really know where to put any of the trees, to be honest. The evergreens I'll put a couple on each side and the rest along the 25ft setback line, but all the wild bird lot, I'm a bit lost. (The septic I just threw in there, it's not to scale but its in that general area)
It looks like its humped in the middle but its not, it's just distortion.
{{gwi:10242}}

Since it's a back yard, have you considered an orchard or vineyard? The land is flat you say, so that would be an easy job.

Also you could break it up with areas of interest with paths and maybe a nice gazebo?

Just thinking out loud.

Basically, are you just wanting to know where to plant all this stuff that you already bought? I suggest that you open the photo of you lot in Microsoft Paint and enlarge it some. (Actually, with the way GardenWeb does photos, we don't know what's its real size is. Maybe it's fine, but here, it looks tiny. view it at 100% in Paint and if you think it needs to be larger, you can "resize" it by %. Experiment. Do a "save as" in case you don't like what you produce and wish to start over.) Then you might use one of the paintbrush tools to plot in where you think you want to plant whatever. Just a dot is fine. (Research each plant--easy on Google--and decide what it could be. For example, the Burr Oak is a large shade tree. The red cedars are a large screen.) Just concoct something out of what you believe these things to be, scratch it out the best you can and post it here for feedback. You can mark trees with dots and label them with the text tool. (It only works when you are working on the drawing at the 100% scale. If you work on it at other sizes, the text tool is inoperable.) You can use the eraser tool to get rid of unwanted "junk" lines & marks on the drawing in order to clean it up a little. (for each drawing tool there is an adjustment scale to make it wider or narrower, so pick what works for you.)