One suggestion if you are going for 9 foot wide roll paper.
If at all possible, purchase your roll paper locally. Shipping on roll paper will eat you up.
Try local theatrical supplies, they are typically a better place to get roll paper than camera stores.
If you have a car with a fold down rear seat, you can very likely get a 9 foot roll inside your car (but the roll has to go to the dashboard). I can get them in my compact car.
And, no black roll paper that I have worked with is all that dense. But, if you separate the background from the subject by several feet, and/or grind on it in photoshop using levels, you can persuade things to be very black.
Enjoy! Lon