This is once again some notation clarification problem that I have: With regarding interior products, say: $i_X\left(\frac{x+1}{x-1}dx\wedge dy\wedge dz\right)$ can we compute this by writing:
$$i_X\left(\frac{x+1}{x-1}dx\wedge dy\wedge dz\right)=\frac{x+1}{x-1}i_X\left(dx\wedge dy\wedge dz\right)$$
Yes, in general if you have a 3-form $f\omega$, $f$ function, and a vector field $X$ on $\mathbb{R}^3$, you have $i_X(f\omega) = fi_X \omega$.