Note: Nether quartz ore blocks can only be mined with a pickaxe enchanted with Silk Touch.
http://www.minecraftwiki.net/wiki/Nether_Quartz_Ore
History Section
This will make it a lot harder to get, as it's a lot more risky with all the lava and stuff. Unless you have fire protection, then the nether is as easy as cake.
No duh, like every other ore block.
Yeah, having armor with fire protection would be a very good idea. Also, you can still use an iron or diamond pickaxe. Its recommended that you have a fortune 3 pick though.