Correct, but if you apply right after your birthday, you'll get almost 5 years out of the initial license.
Irrigation? LOL
It's not illegal to carry there. They just won't let you into the secure area with a gun. Unless you're under arrest, you can just decline to go past that point. It would be your choice to make that a line in the sand. Personally, I'd stand right there and let them sort out their own conundrum.
Zoning, yes. I don't think so on discharging, unless there's an RSA I've missed.
159:26 Firearms and Ammunition; Authority of the State. –
I. To the extent consistent with federal law, the state of New Hampshire shall have authority and jurisdiction over the sale, purchase, ownership, use, possession, transportation, licensing, permitting, taxation, or other matter pertaining to firearms, firearms components, ammunition, or firearms supplies in the state. Except as otherwise specifically provided by statute, no ordinance or regulation of a political subdivision may regulate the sale, purchase, ownership, use, possession, transportation, licensing, permitting, taxation, or other matter pertaining to firearms, firearms components, ammunition, or firearms supplies in the state. Nothing in this section shall be construed as affecting a political subdivision's right to adopt zoning ordinances for the purpose of regulating firearms businesses in the same manner as other businesses or to take any action allowed under RSA 207:59.
II. Upon the effective date of this section, all municipal ordinances and regulations not authorized under paragraph I relative to the sale, purchase, ownership, use, possession, transportation, licensing, permitting, taxation, or other matter pertaining to firearms, firearm components, ammunition, or firearms supplies shall be null and void.
The state already regulates discharge of firearms in the compact portion of a town, in
RSA 644:13. That statute allows police chiefs to give written permission to allowing shooting in the defined area. I don't see any authority to further restrict it.
But please, if I'm wrong, I want to know, so I welcome a cite to the law allowing local ordinances of discharge.
With a couple of tiny exceptions (that are almost unreachable),
all hunting and shooting takes place within city/town limits.
That's a rule, not a law. It's only enforceable by a trespass citation (which would be questionable, since the GC has to be open to the public). You'll get noticed if you're OCing, but it's still legal to CC unless you're told to leave.