1. The simple root found here:
[Program] SimpleRoot .1 ---- 3 Click Root w/ nand unlock!! - xda-developers is a full blown root with nand unlock.
2. Use the above, you should be good. Forget about unrevoked.
3. Go with the link in #1, it wont matter if you take the OTA.
4. The solid ROM builders have incorperated the OTA, but simple root is build to run on the newest OTA, might as well do the OTA.
5. If you use my linked simple root, there is no #22. It is an application that only requires 3 clicks.
6. You should be just fine. I wouldn't go by the link you provided though. Follow the instruction from the developer of whichever ROM you decide on. One that note, there are many good ones, but I've had AMAZING luck with FRESH. It runs beautifully, and he has a few custom kernels you can run as well. He also added his own Fresh Updater app packed in with his ROM.
Best of luck, enjoy the new Evo!!!