0. If you put your EmuNAND-3DS into sleep mode, you don't need to reboot into anything. Just make you you're on your homescreen or in a CIA/eShop-game when putting your 3DS into sleep. Going to sleep with a game booted from the Gateway-card is not advised, because the card may or may not overheat and the battery is drained faster.
http://www.maxconsole.com/maxcon_fo...mode-rule-apply-when-you-are-using-cias/page5
1. Yes, you need an actual OoT card or Sky3DS with a certain save-file installed. You enter the game, press A and the game basically crashes into Gateway-mode.
2. Yes, you need the actual card as well and it works the same. Cubic Ninja is, at least for me, faster and more reliable. You basically boot the cartridge, select an option and you're already in the Gateway-menu.