1. I still suggest sticking with the OEM plugs. If you want to go big, get the platinums which IIRC come stock in the spec.
2. That extender should work. The 'special' spark plug sockets have a rubber washer built in to grab the plug. You could CAREFULLY drop them in and grab them back out with a pair of deep needle nose pliars. Up to you, but it's worth having the proper socket.
5. The racks at the checkout counter will probably have packets of dielectric grease to help keep the plugs from siezing in place. Don't bother. 3 in 1 would probably work just fine.
Another pointer on tightening, read the box they come in. You get the plugs finger tight, then turn the socket either 1/8 or 1/4 of a turn beyond that. It should be on the box.
Be VERY careful when removing the plugs. You are probably going to want to use a breaker bar, make sure the socket is seated properly, and you're not turning at a funky angle. Also, you will hear a sickening 'TING' sound as they break loose. It's ok. Don't have a heart attack until you get the socket out and see that it is intact : P