A few Questions

Hello! I am very new to UE4, and I have a handful of questions regarding features and assets.

#1. Is there a way to change the coloration of a material in the editor? For example, could I change the base grass texture to a darker shade of green, or a separate shade like brown?
#2. Is there a way to change the base size of a model, such as a fern? For example, if I want to make a new type of fern that has the same model as an existing one, but is initially half the size, or twice the size?
#3. Lastly, in line with the first question, can I from the editor change the color of the fern?

Thank you.