Hi Namo. To answer your questions in reverse order, yes you can use the homebrew feats for ToB classes. They are well balanced and are widely considered unofficially to be useful for epic ToB characters.

As for the drow, I just had a quick reminder look through the book, and I don't think you will even be seeing a drow until you are level 29. Each chapter of the book will have you facing a different enemy type for the majority of the chapter. So no matter which creature type you choose it will come in handy eventually.

With regards to the background, there is a lot of material to cover. I am about to go to bed, so I will have to go through and write up the intro material tomorrow. The setting is technically Ashfar, but that is a prime material world, and you will be spending the whole adventure travelling the planes.