Yes, while Sassy Remy is not Full Cuticle Hair like our Luxury Ultima Hair, it is still 100% Virgin Remy human hair and can withstand heat.  Always be sure to use a heat protector product before applying direct heat.
You can color Sassy Remy Natural black color, however, the extent of coloring and/or chemical process depends on the product. We generally recommend a deposit color (going darker) on this hair but some customers have used a lifting color (going lighter) on it and had no issue with it. We recommend doing any chemical process professionally. Generally, it is advised to make any major color changes before installment. This is because the hair might have a slightly different texture or porosity compared to your natural hair.