Ok sorry for the late response but I'll try to elaborate on what each exploit means for the 3DS.
ARM 11 Userland: Most common exploit, used to run basic .3dsx homebrew apps. Some apps may need more permissions (like sysUpdater/FBI for example) many have been patched, but they're still present in 11.2 (latest firmware)
ARM 11 Kernel: Slightly harder to find, allows installation of legit CIAs (CIAs that come preinstalled on consoles) downgrading your console* , access to any save, and RAM editing ?
Latest Arm11 kernel exploit works on 11.1 and possibly more to come.
DSiWare: Since dsi games are installed to the 3DS NAND, if you have a dsiware exploit, you can downgrade NFIRM to 10.4, and then downgrade your whole console. Nintendo's only method of patching it is removing it from the eShop.
Hardmod: Access to NAND, so you can create a backup, and restore it at anytime essentially allowing you to downgrade to whatever firmware you created the backup on, or downgrading NFIRM back to 10.4 like Dsiware. This has never been patched.
ARM 9 Kernel: Full access to the system. Run CFW to patch signature checks, use cheat codes, access to NAND, run custom fonts, homebrew right on your home menu. Latest ARM9 Kernel exploit has been patched in 9.3. A hack called arm9loaderhax, installs a corrupted firm0/1 to allow ARM9 kernel access on system boot, and allows updating sysNAND to the latest version. It is unknown whether Nintendo can patch this or not.
*Downgrading from ARM11 kernel has been patched on 10.7 with something called minimum title check, that prevents installation of titles lower than the allowed versions. However, downgrading NFIRM bypasses this.
So in order to install dsiware, you either need access to your NAND (with an ARM9 kernel exploit), install the dsiware exploit save, then transfer over to the unhacked 3DS. Or using a arm11 kernel exploit to remove the need for a second 3DS.
Hope this helps