iV is not inward delta velocity, it's injection delta velocity.
I missed the dV part of the question. Outward velocity is oV and inward is iV. If your orbital velocity is 7.5k m/s in LEO, then you need to increase your orbital velocity so it goes to the moon, the difference between the two is delta velocity (dV), change in velocity. So, the calculations used for transfer from surface to orbit, and from one orbit to another is usually given in terms of delta velocity, how much faster you need to get to get there, and then dV, how much you need to slow down to get into orbit at the moon or other body, then how much dV you need to lose to descend to the surface. Then you could calculate from fuel capacities, and ship's mass how much fuel you need. Or just let IMFD or TransX do the math.
You have no idea how much this just UNFUZZIED all the things I've been messing around with.The direction of travel in an orbit is prograde, the opposite direction is retrograde, orbit normal+ is perpendicular to the orbital plane toward the north, normal- is toward the south. If you point your ship directly toward the center of the earth and burn, that would be inward velocity, directly away would be outward velocity. So, when you set up a burn to leave, let's say earth orbit to go to mars, for example, you will likely do a burn that incorporates vectors in all three axes, pro- or retrograde, plane change (normal+, normal-) and inward/outward. Time is the final adjustment, to burn at the right time. The effect is more or less, prograde will certainly allow you to escape earth's gravity, but in regard to the solar portion of the transfer orbit will make the size of the orbit larger, the plane change vector will change the inclination, and the inward/outward will change the eccentricity. Hope that helps.