To get an 64GB Sd card working with a 3ds format the SD card to Fat32 as the 3ds doesn't take anything other than Fat32. On Windows use an external program (should be able to find with a simple search). Back Up any files you want off the SD card first.
any way that you can launch to the HBL would work to install K9LH as long as it has the required permissions (9.2), 6.X is pretty much the same as 4.X as they both have MSET its more just depends on what you have to update with, But you can Downgrade with OOT as that what I used on one of my...
Yeah Ninjahax 2(9.3+) would still give the issue of no internet browser, I'm not sure about FreakyHax but OOTHax + Powersave should be able to run without internet as long as the version is supported
That was the problem with 8.1J n3ds as they didn't have the browser it couldn't load and install the exploit, I would recommend update with cart to 4.X where you can use MSET or Spider to load into a Sysnand mode (RxTools Dev Mode) where you can update to 9.2 using Sysupdater then install K9LH...
1. you can update reinand to 11.0.0 fine
2. browser/menu hax work on 9.2 which is required to run reinand, menu and browser are only broken anywhere past 10.5
OOT is just another way to get OOT Hax
CFW is a way to get "Legal Backups" and have region free built in
AuReiNAND is a CFW it just requires the Homebrew Loader and 9.2, Which is Ninja/OOT/Smash/Browser/tubeHax
CFW isn't that hard if you can follow instructions, We have had many 3ds updates and all we do is just update the CFW. You won't loose Eshop, The only way is if you change your 3ds region. and for the OOThax tutorial https://gbatemp.net/threads/tutorial-how-to-install-oot3dhax.396339/
If you have a CFW you can still access the Eshop, you can also play almost any Virtual Console Game on the 3ds native Emulator or one of the Homebrew Emulators, as for bypassing region change, you can either find a copy of Zelda:OOT for $20 thanks to the Nintendo Selects and a power save or...
It's not the movies or games downloads that I would worry about, like breaking into networks, downloading encrypted things, spying on network traffic. I have seen so many "Top Secret" seals on files when I was a kid
I was obsessed with finding UFOs, a surprising amount of US files where stashed on computers in other countries, China back in the early 90s omg sooo much