Goes without saying (but I'll say it anyways) IANAL.
Most state-level restrictions on discharging firearms seem to have to do with hunting or threatening/shooting people. As long as you aren't frightening, threatening, or shooting animals / people there's a bit less to worry about.
After a (very) brief search the only state-level restrictions I found that are not
directly related to hunting / threatening people are a prohibition on "frightening" migratory animals and a prohibition on shooting within 15 yards of a state-owned road:
7 Del. C. § 717 Frightening or harassing migratory birds; penalties.
Any person who shall frighten or harass migratory birds while at rest on the property of another by use of a rifle, shotgun or any other weapon, shall be guilty of a class C environmental misdemeanor.
7 Del. C. § 719 Discharge of firearms on or near public roads and public rights-of-way; penalty.
(a) No person, except in lawful self-defense, shall discharge any firearm while on or within 15 yards of a public road or right-of-way unless it is a road or right-of-way within an area controlled by the Department of Natural Resources and Environmental Control, the Department of Agriculture of the State or the United States Department of the Interior and is designated by the respective department as an area open to hunting or trapping.
(b) No person shall shoot at any wild bird or wild animal while it is on a public road, nor shall any person shoot across a public road or right-of-way at any wild bird or wild animal.
(c) Whoever violates this section shall be guilty of a class C environmental misdemeanor.
Obviously, hunting animals and making physical / verbal threats against people are pretty highly regulated.
Note that the discharge of weapons falls outside of state preemption, meaning that counties/towns/cities can regulate it. You should double-check the local/county codes for your area. Some of the local restrictions can be found in this document, near the end:
http://www.deloc.org/docs/Delaware_Firearms_Laws.pdf
Also, you may need work / building permits of some sort depending on what sort of "improvements" to the land you plan on making but I really have no idea about that.