hey man, no card can support 3ds rom on 3ds 7.1.0. at the moment gateway 3ds or r4i gold 3ds deluxe edition just can support 3ds game on 3ds 4.1 - 4.5. so no link can be provided for you to download the firmware. but i believe it will come true in the future. so just wait the moment.
r4i gold 3ds can work on v7.1.0-15,yet,it didnt support 3ds rom. while gateway 3ds currently only work on N3DS V4.5-4.1.So,i'm afraid, you can just buy a r4i gold to play nds games, you can download the latest wood firmware from r4ids.cn and here is a detailed setup guide for you : http://www.modchipwarehouse.com/r4i-gold-3ds-flashcart-for-3ds-xl-3ds-dsi-ds-lite-p-1.html
no, no flashcard support play 3ds games on v7.1.0-15. gateway 3ds can emulate v4.5 console to v7.1, means you can play v4.5 above games, but your 3ds should stay in v4.5.
