Brian, I'll answer your questions one at a time at the "**"s below:

"If a strike-slip fault dips significantly, what affect does that have?"
**The distance from the actual breaking faults is really important to ground motion, especially outside of sedimentary basins (hence, the precariously balanced rocks of Jim Brune at distances > 10 or 15 km from big southern California desert faults, or maybe the Egyptian Obilisk at Istanbul near Blue Mosque, there since 5th century. If the fault dips away from Istanbul, much of the rupture will be farther away than the sea floor trace. ***

Does it mean there will be a non strike-slip component to the quake?
**maybe, maybe not. It means that you can take up extension or contraction by oblique slip so separate thrust or normal faults are not required. A vertical fault does not solve the space problem at fault bends.**

Does it increase the fault plane area enough to increase the potential magnitude?
**Yes. But, if it is dipping 70 or 80 deg, not by much. The Japan M9 dipped 14 deg. **

Does it affect the radiation pattern of the seismic waves?
**Not my expertise, but I think the answer is "yes", and I think it is important**.

Which then could change where the damage ends up?
**yes**

Chris