sure, do that, as for the 3 other files, they are files required to generate the arm9loaderhax installer, the new3ds10.firm is the decrypted firm of 10.2 new3ds (required to trigger arm9loaderhax), the new3ds90.firm is the firm from 9.0(?) new3ds (it is required as it's larger than the 10 and thus a small payload can be append to it, to load a larger payload) and secret_sector.bin contains data related to generating N3DS only AES keys, including the one used to decrypt the kernel9 from firm (it needs to be modified in a way that the key used to decrypt kernel9 will decrypt the first instruction into a jump to the payload location), as you can see, all 3 files are used to trigger arm9loaderhax.
If you want more information, i recommend you reading
this post on delebile's "blog" (not sure if it's supposed to be a blog or whatev')
edit : if you see that i made a mistake or wrote some nonsense, don't hesitate to tell me ^^
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reading/decrypting firm1/0 partition to ram and firmlaunching it ?
and also, have you found a way to detect if no SD card is inserted without crashing the system ?