Normal cheapest carton sheets from every paper or gift shop. Those textures are made with coffe or watercolour and the final "magic" is in textures from PC ! My scanner is dumb! (I fight with it a lot¨!)
Umm. NO. Just experiment. You have to take a blank paper and try everything what comes on your mind! You just need to buy more brushes. At least 1 tiny, 1 small, 1 normal and 1 large. Personally, I use only 3 or 4 brushes all the time.