The offset of a wheel is the amount of distance the profile of the wheel sits based on the center section of the hub. the offset will make a wheel stick out further from a car, thus being more flush with a wider body. A wheel with a "0" offset is centered. A wheel with a "positive number" offset, will stick out further. Likewise, a wheel with a "negative number" offset will be closer the car.
Here is a pic to better explain:
Regarding ABS, this has nothing to do with it. If you order the ABS tires from sflrcdrift.com, they will fit over the standard 10th scale, 26mm wheels.
I hope this helps
URC